


The Anthem of a Ghostly Goo

by Emme2589



Series: Luigi's Mansion 3 Retold [1]
Category: Luigi's Mansion (Video Games), Super Mario & Related Fandoms, Super Mario Bros. (Video Games)
Genre: Angst, Blood, Brotherly Love, Fluff, Found Family, Friendship, Gen, Hurt/Comfort, Major Character Injury, Poisoning, Psychological Trauma, Vomiting, mario is a good brother, polterpup is a good boy
Language: English
Status: Completed
Published: 2020-05-13
Updated: 2020-05-20
Packaged: 2021-03-02 19:14:42
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 13
Words: 24,044
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24151894
Author URL: https://archiveofourown.org/users/Emme2589/pseuds/Emme2589
Summary: Gooigi doesn't know what it's like to be alive, but the longer he travels with his new friends, the more he understands the meaning of family.
Series: Luigi's Mansion 3 Retold [1]
Series URL: https://archiveofourown.org/series/1754224
Comments: 21
Kudos: 93





	1. Chapter 1

As far as being alive goes, he didn't know what it was like.

The first memory he could recall clearly was floating suspended within a jar. He could see the green glow on the computer console as he rested on the desk. He heard an excited exclamation, a question, though what it was escaped him at the moment, but he did remember not being able to answer.

 _"Oh, I'm so sorry!"_ a whirring from the computer, a few taps on the keyboard, _"You can't do much in that jar, can you? Oh hoho! Let me release you, then! This will only take a moment!"_

His jar was lifted, jostling him from whatever could count as drowsiness, and he remembered the distinct smell of copper, and the fact that the glow in the jar did not stick to the sides of the glass.

He was poured onto the ground, becoming a puddle, stretched thin until his senses were muted. It didn't hurt exactly, but it wasn't very comfortable. He wished he could return to the jar.

 _"Oh, come now!"_ the voice tittered at him, _"You can get up! Concentrate, young one! Reform!"_

He wasn't entirely sure what the voice was talking about, but he tried to concentrate on something, though the liquid spreading over the floor was diluting his thoughts. The first thing he registered was his own body. He had a body. He reached for it, a tangled mass of limbs becoming more coherent. The first thing he was able to form was his head. A mop of short hair beneath a cap. Thick eyebrows. A large nose framed by big, round eyes, and a smooth moustache. Next was his arms, which he used to pull himself out of the puddle. They were covered by long sleeves, his hands hidden beneath wrist-length gloves. As his torso appeared with his repeated efforts, he could make out overall straps, round buttons, a shirt with a high collar, all above a soft stomach. A stocky build. The last thing he formed were his legs. The overalls continued down them until they ended at a pair of shoes. He was shaky on them at first, but someone was quick to reach for his outstretched hand as he stumbled, helping him stand up with a triumphant laugh.

"Yes! Yes I knew it!" the voice, as it turned out, was coming from a short old man. He let go, but kept his arms outstretched until he was assured the gooy mass would hold his own weight, "Perfect! I knew this would be the one! Welcome to the world, my glorious creation!"

He tried to comprehend the words as they were said, which was easier now that he was reformed. As soon as he understood what the old man was saying, he pointed to himself, shrugging as if in question.

"Yes, you!" the old man rubbed his hands together, "Oh, this is so exciting! I'm so sorry I failed you so many times, but look at you! Fully reformed without so much as a ripple! Amazing! I can't wait for you to see the rest of the world! I have plans for you, Gooigi! Wonderful, glorious plans!"

He inspected his arm as the old man was talking, until he registered the name he'd uttered in his rambling. He could see his own reflection in the computer monitor, and he saw something that made him remove the cap to see the letter emblazoned on the front; A stylized capital "G".

"Gooigi." the old man repeated, "It's your name. I modeled you after the best ghost hunter I know! I would want nothing less as my successor, after all!"

Gooigi let a gurgle escape him. It wasn't a bad name, by any means. He could get used to it.

He did have memories from before this first one, but they were a mess of sights and sounds. Bright neon colors. Screaming. All above tearful apologies and declarations of a failed experiment. When Gooigi had asked about these fuzzy memories, his creator, the old Professor E. Gadd, would swallow guiltily and explain little more than _"You did not come into the world smoothly."_ The smell of copper never went away, though it did fade overtime.

After this first memory, he spent most of his time in the jar. Eventually this turned into a glass container attached to a peculiar vacuum, but it felt the same as always. He slept during this time, or thought, though there wasn't much to think about. E. Gadd only brought him out to teach him, mostly about ghost hunting. He was even fitted with his own goo vacuum for when he left the tank, making him wonder if someone else was intended to wear the first one.

The next coherent memory he had was the first of many, and it would prove to be more than he expected from his hours inside the jar.

It was the middle of the night. Gooigi was in his jar in E. Gadd's portable lab. Apparently, E. Gadd had been invited for the prospect of ghosts, an offer he couldn't refuse. If Gooigi had more of a reference for deals that were too good to be true, he may have considered that a red flag, but as it stood at the moment, he was simply waiting for E. Gadd to return.

It took longer than he was expecting.

By the time he was jostled from his thoughts, he faintly registered that he was being poured into the Poltergust G-00, his tank, but what really made him snap back to reality was the fact that someone was wearing the vacuum. His senses were more condensed when he was in a container, so he reached out to see who it was.

The first thing he registered were bright blue eyes staring back at him from his reflection. It was only a flicker, but Gooigi was stunned. He had never known that eyes could be blue. He was seeing through those eyes, nodding along to whatever the professor was saying, though Gooigi wasn't listening. It wasn't until a gloved hand came up to rub the back of his head when he realized who's eyes he was seeing through. This was Luigi.

"Now, my boy. Why don't you follow me outside?"

The world looked different through Luigi's eyes. For one, nothing was muffled. When Gooigi was jostled or unformed or stretched, sensations were slowed as if his head were dunked underwater or stuffed with cotton. Luigi had none of these limitations. His senses were clear no matter how fast he was moving or how quickly he whipped his head around. At the same time, the world appeared darker, smaller. The mist obscured things that were too far away. Luigi's footsteps sounded different, too. They were more solid, creating sharp tapping sounds on the concrete, as opposed to the faint splashing that Gooigi's footsteps always made.

E. Gadd positioned Luigi in a specific spot before he hit a switch and a wooden cage came crashing down.

A few things happened at the same time.

Luigi jumped, startled enough that his feet made him leap a foot into the air. Gooigi was stunned back into his tank. He thought his own emotions were overwhelming, but Luigi's fear shot through him like a bolt of lightning. It was actually so painful that he had to restart his thought processes because the feeling of danger was like a gunshot. He wondered if he was dying. Luigi must have felt the rebound, because he stumbled on his feet once he'd hit the ground, almost falling directly onto the pavement below.

Luigi grabbed the bars of the cage, his fear still clear in his voice, though it wasn't nearly as electrifying as before, "H-hey! What gives!?"

"Oh ho! You've fallen directly into my trap!" E. Gadd gave a good-natured chuckle, "Relax, my boy! I'm just kidding! But I want you to use your new partner to get yourself out!"

Luigi stepped back from the bars, "How?"

"Easy! There's a green button on your flashlight! You should press it."

Gooigi felt a tug as soon as the button was pressed. He understood. He should leave the tank, so he did.

He pooled on the ground before reforming. He was used to it by now, after all. As soon as his senses sharpened, he saw Luigi turn around. Those blue eyes fell on him, and Luigi stumbled back. Gooigi could no longer feel Luigi's emotions or see through his eyes, but his guess was that Luigi was unsettled by him. He could hardly blame him if that were the case. He was a copy of him, after all. A copy made of goo. Still, he wasn't even sure. He wasn't good at reading faces.

"Luigi? Meet Gooigi!" E. Gadd proclaimed, "Isn't he amazing?"

Luigi slowly nodded, his eyes never leaving his translucent doppelganger, "Um, yeah. How did you make him exactly?"

"A lot of ghost hunting and a lot of patience! Now, Gooigi can do many things that any ordinary person cannot! Just watch!" E. Gadd cleared his throat, "Gooigi, go outside the cage!"

Gooigi looked from Luigi to the bars of the cage. Once the words registered, he walked towards the bars, pushing against the ground until he had gone right through them.

Luigi's eyebrows shot up to his hairline, "Oh!"

"Now you try!"

"Um, okay." Luigi tugged on his collar, looking around for whatever the cage was connected to, "Uh, Gooigi? Go towards that dial."

There was a wheel connected to a chain which ran the length of the garage, ending at the cage that trapped Luigi. Gooigi started to make his way toward it when he caught something shining on the ground. He stopped just before touching it.

"Luigi, he can't touch water." E. Gadd explained, "He'll melt if he does, so keep that in mind."

Luigi tapped his chin, "Well, Gooigi, you can go around the water, can't you?"

Gooigi looked at the ground around him, carefully finding a path that took him around the puddle until he stood in front of the dial.

"I know he seems pretty clueless, but he's still learning." E. Gadd said.

"Okay." Luigi cocked his head, "Gooigi, hit that wheel with your vacuum."

Gooigi did, and the wheel turned, lifting the cage that had kept Luigi prisoner.

"Excellent!" E. Gadd stepped back as Luigi exited the cage, "Now, Gooigi may be tough, but he's not invincible. If you're going to get out of here with your friends, you need to protect each other. Alright?"

Luigi watched Gooigi return to his side, "Okay. I can do that."

"Then get out there and hunt some ghosts!"

Luigi sighed, hitting his forehead with his outstretched palm. Gooigi had a feeling that he wasn't looking forward to that.

***


	2. Chapter 2

One thing that was beginning to annoy Gooigi was the fact that Luigi would call for Mario _constantly._ Opening a new door? _"Mario?"_ Been alone for too long? _"Mario?"_ The lights cut out suddenly? _"Mario!"_ He couldn't even begin to guess why he did that. Luigi was a grown man, and yet he was shivering and shaking, calling out for his brother like a child calling for their mother. In Gooigi's opinion, which was of course limited by his lack of experience, he probably had a better chance of purging this building of ghosts on his own.

"Okay, Gooigi." Luigi summoned him with the green button, and Gooigi appeared, "Metal spikes. Do your thing."

Gooigi gave no response, and Luigi ran an exasperated hand down his face.

"What, you haven't got the hang of this by now?" Luigi pointed to the rope on the other side of the spikes that were protruding from the floor, "These spikes will hurt me. Go through them and hit that rope with your vacuum."

_That_ got Gooigi moving. Getting through the spikes was slower than his normal walking speed, but it was a far cry from the cuts and puncture wounds Luigi would have gotten attempting the same thing. Gooigi pulled the rope, and the spikes disappeared into the floor.

"Okay hold that." Luigi quickly crossed the gap, "Whew. You can let go, now."

Gooigi let go of the rope, and the spikes returned behind them.

"Thanks. You know, this place is giving me the creeps. I hope Mario isn't too much farther."

There was that name again. Luigi had tried to explain why he was still in a haunted hotel despite his fear of ghosts, but it had gone over Gooigi's head. His only reference for who Mario was came entirely through Luigi, and according to him, Mario was perfectly capable of saving himself.

Although, E. Gadd had told him that people aren't very good at evaluating their own merit, so Luigi was probably more capable than he thought he was.

"Okay, come with me through this door. I have a bad feeling about it."

Luigi had been right to think that, as the next room was brimming with ghosts. Gooigi noticed the way the temperature dropped when they entered. The lights were off, and there was a strong copper smell. Gooigi noticed the way Luigi would shiver upon entering haunted rooms, his grip on the flashlight tightening. When Gooigi was in his tank, he noticed that Luigi would get a prickling on his skin, like a pins-and-needles kind of sensation, and it fascinated him. He found himself thinking about that as he and Luigi cleared the room of ghosts. As soon as the last ghost disappeared into the vacuum, the lights came on and the cold receded.

"Oh yeah!" Luigi did a little dance in place, "We did it! Wahoo!"

He glanced at Gooigi, who didn't move.

Luigi rolled his eyes, "Well, thanks for the help, Gooigi. Recall."

Gooigi dissolved into a liquid, returning to the tank. He felt Luigi's annoyance with him, but he couldn't for the life of him figure out what he had done wrong.

He remembered the way Luigi seemed to be unsettled by him. Maybe Luigi was afraid of him. Maybe Luigi _hated_ him.

Somehow, he didn't like that thought.

***

The two beams of light swept over the hallway, each keeping a sharp eye out for anything that might jump out at them with no warning. Gooigi wasn't particularly easy to scare, but he couldn't help but feel unsettled by the darkness and the silence. Sometimes a mouse or a bat would appear out of nowhere and Luigi would jump out of his skin. If Gooigi was in his tank when this happened, he couldn't help but focus on Luigi's pounding heartbeat. It would sometimes get so fast that it felt like it would leap right out of his chest. Gooigi would sometimes press a hand to Luigi's chest or back, just to make sure his heart wouldn't suddenly stop.

"I'm fine." he would say, but Gooigi wasn't sure if he meant it or not.

Luigi hit the next elevator button, "Hey Gooigi, are you actually alive, or...are you just good at following directions?"

Gooigi didn't know. He had been thinking about the same thing their whole adventure. He wasn't sure how to communicate that though, so he just stood there and did nothing.

"I mean, clearly there's _something_ going on in your head...but do you have a personality? I know, weird question, but you don't respond to anything I say unless it's a direct order, so do you just recognize words? Do you not _know_ how to respond, or do you have nothing in there to respond _with?"_

Gooigi almost felt his eyebrow rise. He didn't know what a personality was, so he couldn't say if he had one or not, but it seemed as if Luigi was talking to himself at this point.

Luigi glanced at him, then he gave a heavy sigh. Was Luigi annoyed with him again? Why? He hadn't even done anything!

_Maybe that's why._ he realized with a start, _Maybe you should say something._

He didn't want to. He didn't like talking. It felt unnatural, and his voice was difficult to understand anyway. He could cry out in pain or laugh occasionally, but forming actual words was hard.

"Ah well. I guess I won't know if you can't communicate with me." Luigi then mused, mostly to himself, _"Maybe I should teach you sign language..."_

Gooigi didn't know what that was either, but he didn't care. Luigi was annoyed with him. Was Luigi annoyed with Gooigi as much as Gooigi was annoyed with him?

Was he not being fair?

He spent the next entire floor wondering if communication would help. He certainly wouldn't like talking to someone who couldn't respond.

***


	3. Chapter 3

It didn't help that Gooigi was an impassive, emotionless blob. He was good at following directions, in fact he was eventually starting to catch on and figured things out even before Luigi did, but that didn't mean he felt as though he were real. He was more like a robot, going through the motions like gears turning in a well-oiled machine. Effective and helpful, sure, but it was so lonely that Luigi would almost rather be totally alone. At least then he wouldn't feel like he was babysitting a plate of jello.

Luigi swallowed, hiding a yawn behind his hand, "I feel like we're getting nowhere..."

Gooigi didn't reply, though he did cock his head slightly.

Luigi entered the elevator, pressing the button for the ground floor, "Okay, we only need one more button left, so let's get to the-!"

The elevator jerked, and Luigi's breath caught in his throat. He gasped, forcing air into his lungs.

They weren't moving.

Luigi hit the button again, and again. His chest was tight. His face was flushed, "No no no! Please! Don't do this! Not now!"

There was another massive jerk, and the elevator began to fall. The screeching was accompanied by ghostly laughter that rattled around in Luigi's skull, making his head spin and spilling tears from his eyes.

The elevator continued to fall faster and faster. Spots danced in Luigi's vision. He swayed, teetering on the edge of unconsciousness. He was close to losing himself as he went into full-blown panic mode.

He didn't register when they hit the ground. The only indication that they had stopped moving was the fact that Luigi's stomach heaved, and suddenly he was glad to be running on an empty stomach.

He realized why he hadn't felt himself hit the ground; Gooigi had both arms wrapped around him, holding him up so that his gooy body could absorb the shock of the fall. Luigi let himself be held until the blood rushed back into his head and the smell of copper saturated his nose and mouth. He pushed Gooigi away so he could dry-heave onto the floor, coughing until his throat was sore.

Luigi let his head fall onto the floor. Out of everything that could have possibly happened, a trap wasn't what he was expecting. God, he could really use a vacation after all of this. The irony of the situation almost made him laugh, but the sheer stress weighing him down was enough to make him choke back a sob instead.

On top of all that, not only would he likely never see his friends or his brother again, but he was trapped with an ectoplasmic goo creature that shared his likeness.

Luigi turned to Gooigi as he stared emotionlessly at him, almost stiff for someone with jello physics. Though Gooigi had saved his life just now, he appeared as blank and impassive as ever.

Luigi scoffed, "What are you looking at?"

Gooigi didn't reply.

"You probably aren't even alive..." Luigi sucked in a breath of air through his teeth, "You just follow basic instructions!" his throat burned as he cried, "You have been giving me no indication that you can feel anything! All I wanted was for my friends to be safe, but I can't even have that much! For all I know, I'll never see Mario again!"

Luigi dry-heaved again, his arms shaking violently as they struggled to hold him up. He hit the ground with his fist, watching his own tears fall onto the ground beneath him.

Gooigi still didn't reply. He didn't even move aside from a slight tilt of his head.

"Stop looking at me like that! You're not helping! You're not even real, _you're just a stupid science experiment!"_ Luigi pushed him so that he stumbled and fell backwards.

Gooigi hit the ground. Luigi's face softened, and he felt a pang in his heart.

"No, no...I'm sorry..." Luigi gingerly helped Gooigi stand up, "If you do have something going on in there, I don't want you to have memories of abuse..."

He lingered as he held Gooigi's hands. They didn't feel at all like his own, despite being the same shape. It literally felt like he was holding onto jello.

"Please." Luigi lifted Gooigi's head to look him in the eye, "Please give me _some_ indication that you can hear me! Anything! Let me know there's someone in there!"

Gooigi stared at him, then he looked down at Luigi's outstretched arms. He lifted his hands, taking Luigi's hand in both of his own and giving it a firm squeeze.

Luigi blinked.

"Was that it?" his voice shook with hope, "You can hear me?"

Gooigi looked down at Luigi's hand in his.

"Here, when I ask you a question and you want to answer yes, nod like this."

Gooigi mimicked his action, bobbing his head up and down.

"Now, if you want to answer no, shake your head like this."

Gooigi shook his head from side to side.

"Okay, now tell me; Can you understand me?"

Gooigi thought for a minute, then he nodded.

"You can!? Really!?"

Another nod.

"Here, answer no so I can tell you're not answering randomly."

A head shake.

"You can hear me..." Luigi gave him a hug, "I'm not alone in here after all..."

Gooigi didn't return the hug, but he did loosen up a little, caving slightly under Luigi's hold.

Luigi let go of him, "Hey, um...I'm sorry for what I said, and I'm sorry for pushing you. I don't really think you're useless or anything. I know, I shouldn't say things I don't mean. I didn't want to hurt you. I'm sorry. No hard feelings?"

Gooigi looked away, then he gave Luigi a thumbs up.

"Heheh. Thanks, Gooigi." Luigi sighed, stepping back to let his arms fall to his sides, "So...how do we get out of here?"

Gooigi inspected the elevator doors. He pried his fingers between them, flattening them so they would fit. As soon as there was a tiny gap, he slipped through, making a squelching sound as he disappeared. In the next second, the elevator shifted again, and the doors opened with a _Ding!_

"Whew..." Luigi took his cap off to wipe the sweat from his brow, "Thank you."

He replaced his cap as he stepped off the elevator. Surprisingly, they weren't even on the bottom floor. The elevator must have simply gotten stuck.

"Okay..." Luigi clicked his flashlight on, "Let's go. I'm not getting back on that thing."

***

Luigi was shaking as he pointed his flashlight around every corner. He held up one hand to halt Gooigi in his tracks until he determined it was safe to proceed. After so long trekking through all the floors of the hotel, the Poltergust G-00 was starting to feel so heavy. He could really go for a plate of spaghetti right about now, or at least a glass of water. He was so tired that he was dragging his feet, only barely managing to flinch when something startled him.

Finally, Luigi's legs gave out from underneath him. Gooigi caught him just before he hit the ground, letting out a gurgle of distress.

"'m fine, 'm fine." Luigi tried to stand up, but he couldn't even hold himself up on his elbows.

The VB began to ring, and Luigi answered with a shaking arm.

_"Luigi! What happened to you!? Are you hurt!?"_

Gooigi swept his eyes over Luigi's body, but there were no injuries that he could see.

"I...I'm fine..." Luigi tried to stand again, "I'm fine, I need..."

_"Listen, Luigi! You're no good when you're worn out! Get back to the lab immediately! That's an order!"_

E. Gadd hung up, and the TV portal activated on its own. Gooigi lifted Luigi high enough to get him through, then he jumped through himself.

As soon as they were in the lab, Luigi was out like a light, snoring lightly. Polterpup immediately ran to Luigi's side, kissing his face and barking worriedly.

"Easy now, pup." E. Gadd shooed the ghost dog away, "Let him rest. He needs it."

The three toads Luigi had saved so far rushed to his side. One of them placed a hand on his forehead. It was cold and clammy, covered in a thin layer of sweat.

"Gooigi." E. Gadd took him aside, "You were almost there, weren't you? I want you to go back to where you left off and finish the level you were on."

Gooigi glanced at Luigi, whose chest was slowly rising and falling as his fight-or-flight response subsided in his sleep.

"I know, you'll be alone, but not for long." E. Gadd said, "Mario's painting isn't even in the next room. You have your dark light, so once you free him, you can return to the lab and we can discuss our next strategy. You know what to do if you find yourself in danger."

Gooigi hesitated, but eventually, he took Luigi's Poltergust so he could go off on his own.

"Okay. Take the VB, too. Just in case."

He did, stashing the headset inside his gelatinous body, before he headed back through the portal to save Mario.

The hallway was darker than he swore it was when he left. The mist was suffocating enough that he used the vacuum to clear some of it, though eventually it was too thick to properly see the floor even with his efforts. E. Gadd was right, Mario's painting was at the end of the hall, but he only recognized him because of his red cap and shirt. The mist here was too thick. He realized that because Mario needed oxygen, the mist might end up hurting him if it was more than just vapor, so instead of freeing Mario in the hallway, Gooigi took the painting down and headed back towards the elevator with it. Once the hallway was clear, he set it down and turned on his dark light.

Mario fell flat on his face as soon as he was out, jumping up and lifting his fists.

Gooigi lifted his hands, hoping it was close enough to a sign of surrender. He stayed still like that until Mario let his hands fall. Gooigi gestured for Mario to follow him, getting out the TV portal to return to the lab. He pointed towards the screen before climbing inside, hoping Mario didn't think he was being malicious or deceitful.

Evidently, Mario did follow him, and as soon as his feet hit the ground, he saw Luigi, still passed out on the floor.

_"Luigi!"_

He made a beeline for him, pressing his ear to his chest, and sighing in relief when he heard a steady heartbeat. He took Luigi's hand, giving it a gentle squeeze as he watched him sleep.

"He's had a long day." E. Gadd explained.

Mario looked up at him, "E. Gadd!? What are you doing here?"

E. Gadd chuckled sadly, "It's a long story."

Mario pointed at Gooigi, his mouth open like he wasn't sure what to say.

"Oh, Mario, meet Gooigi! My greatest creation yet!"

Gooigi truly wished he could read others better than he could. He couldn't even begin to guess what Mario was feeling about him. The only emotion he could clearly discern was confusion, but otherwise, he guessed based on the single furrowed eyebrow and the slight grimace that at the very least, Mario didn't know what to make of him.

The lab lapsed back into silence, so Gooigi had plenty of time to think, kneeling on the ground as he did just that.

His head had never been so full before. In all his experiences, he had learned so much in such a short span of time, and yet with all his newfound knowledge, he hadn't noticed that Luigi was on the brink of collapse. He'd never felt so guilty before. Luigi could have died because he was pushing himself so hard, and Gooigi didn't suspect a thing. Well, as long as they had Mario with them, maybe he could tell Luigi was tired before he collapsed. He could only hope.

"Gooigi."

Gooigi looked up as E. Gadd knelt in front of him, adjusting his glasses to see him properly.

"I know what you're doing." he said gently, "Don't you dare blame yourself for this. Luigi fainted because he was recklessly charging forward without any consideration for his own safety. He's done it before and he'll almost certainly do it again. Don't even try to apologize for it, you hear me? It wasn't your fault."

Gooigi garbled, crossing his arms indignantly.

"Don't give me that, young man! This would have happened no matter what! For how much Luigi fears all these ghosts, he's surprisingly stubborn."

Gooigi could feel Mario's eyes on him. It made him uncomfortable, but he didn't know how to communicate that.

"Besides." E. Gadd continued, "I saw how you caught him in that elevator. I'm sure you saved his life."

Gooigi's thoughts were getting more and more jumbled. He hadn't even thought about saving Luigi, he had just done it. Even though he wasn't very fond of him...it felt wrong to let Luigi get hurt.

He could _really_ feel Mario staring now.

Luckily, he didn't have to lose himself in his thoughts for much longer, as a timid voice rang out drowsily from the darkness.

"Mario?"

***


	4. Chapter 4

Luigi's eyelids were heavy. Every muscle in his body protested his movement, but he couldn't let himself rest now. He was doing something important, he was sure of it. Why couldn't he wake up?

Finally, his sore eyes landed on the ceiling of the lab. He caught a familiar shock of red, and his breath hitched. He could hardly believe it.

"Mario?"

"Luigi!" Mario helped him sit up, "Are you okay!? What happened!?"

Tears spilled down Luigi's face. He covered his mouth, hiccuping as he stared and softly sobbed.

Mario wrapped Luigi up in a hug, and he was happy to reciprocate.

_"Mario..."_ Luigi mumbled, _"Mario Mario Mario..."_

He was only just realizing how tired he was. How utterly drained he had become overtime. His emotions rolled over him in waves, and yet he couldn't help but feel blank. His vision and hearing were filled with static. All he could register was the soft cloth of Mario's shirt, and at the moment, that was just fine by him.

Finally, Luigi's tears had dried up, and he lifted his head from Mario's shoulder. He took a shaky breath of air, keeping his hold on Mario's arms to steady himself. He cleared his throat, then he swallowed.

"Mario, how did you get here?" Luigi's voice was hoarse, "Weren't you in King Boo's painting?"

Mario shrugged, gesturing towards Gooigi, who had returned to his blank stare.

"Gooigi?" Luigi waited for him to turn towards him, "Did you go after Mario by yourself?"

"He's not helpless, Luigi." E. Gadd returned to his chair, "I intended him to be my successor, remember? I figured you'd stop pushing yourself so hard if you had your brother back already."

Luigi swayed, holding Mario tighter to keep his balance.

"Luigi, you're exhausted." E. Gadd scolded, "You need to sleep."

"No." Luigi tried to stand, but fell back into Mario's arms instead, "I can't. Peach is still..."

"Peach has a better chance of being saved by a well-rested Luigi rather than a dead-man-walking Luigi." E. Gadd remotely locked the lab and turned all the monitors off, "I'm not giving you a choice. Either you sleep, or we stay in this lab for the rest of the night."

Luigi glared at him, a spark of righteous anger flaring in his chest. It was quickly stifled by a yawn, however. Okay, so maybe he _was_ exhausted.

He decided to stop fighting, and then he was fast asleep.

***

Luigi was in a long hallway, not unlike the ones he was used to seeing in the hotel. He was eager to find his friends and get out already, but he couldn't find any more leads. Sometimes he heard the chilling laugh of King Boo, and he ran faster.

Although, the longer he ran, the more he suspected the hallway would never end.

He ran faster, his lungs wheezing. The smell of oil paint and turpentine filled his senses, burning his nose and making his eyes water. The hallway began to grow brighter, becoming closer to abstract shapes than solid wood and wallpaper.

Finally, Luigi made it to the end of the hallway, where a picture frame hung on the wall. Peering into it, he could make out Mario calling out to him, desperately reaching for him but unable to penetrate the frame.

It was then that not only did he have the Poltergust with him, but he was on the wrong side of the frame.

He was trapped inside his own painting, with no way out.

Luigi gasped, his heart thundering in his chest. He automatically reached out, and another hand grasped his.

"Luigi, it's okay. You're safe. I'm here."

Luigi calmed at the voice, though he still sat up to give its owner a hug, "Mario?"

"Yeah. It's me." Mario gave his torso a squeeze, "Nightmare?"

Luigi sighed, then he nodded.

"It's okay. I've got you now."

Luigi turned to free one of his arms in the embrace, rubbing the dried tears from his face, "How long was I out?"

"About four hours." E. Gadd turned his chair towards him, "How did you sleep? Do you feel any better?"

Luigi finally stood up successfully, leaning on Mario for support, "I'm a little sore, but I feel much better."

"Good. I'll allow you to leave now." The lab door unlocked with a hefty _click!_ "Be careful, Luigi. Don't strain yourself. You wouldn't want to have another fainting spell."

"Okay."

Luigi replaced the Poltergust G-00 on his back, clicking on the flashlight as he left the lab. Gooigi followed him, naturally, but Luigi didn't expect a second set of footsteps following behind him.

He turned, "Mario?"

"What? You think I'm going to let you go into danger alone?" Mario gave him a pat on the back, "What kind of brother would I be if I did that?"

"But you don't even have a Poltergust. These aren't normal enemies, bro. How are you going to defend yourself?"

Mario shrugged him off, "I'll find a way. You know I always do."

"Yeah, but I'd feel bad if I didn't at least give you something..." Luigi searched his pockets for anything useful.

Just as he was growing frustrated, Gooigi offered a metal object. It was Luigi's flashlight; One that wasn't connected to any version of the Poltergust.

"Aha!" Luigi took it from him, "Thank you, Gooigi. This flashlight has its own strobulb installed, so you can use it to stun ghosts. It won't work for all of them, but it should at least give you an advantage. If nothing else, it helps to see. Just don't shine it in my eyes. Gooigi did that a few times."

Mario took the flashlight, clicking it on and shining it around the garage. Gooigi tapped Luigi's shoulder, drawing his eyebrows in what he hoped was a frown.

"Hey, it's okay. I forgive you." Luigi led the way down the hall from the garage, "Now let's hurry. Peach's painting could be anywhere by now."

***


	5. Chapter 5

Over the two days that Gooigi had been invented, he began to notice that though he had been modeled after Luigi, the two of them could not be more different from each other. Gooigi's emotions existed without a doubt, but they were relatively mild. It was easy for him to stay calm. By contrast, Luigi's emotions were wild, almost frantic. Fear was most common, but a few times he'd seen him in confusion or frustration, as well as intense sadness, disgust, pride, and even an excitement that rendered him unable to hold still, breaking into whole dances as he proclaimed, "I did it! Luigi number one! Wahoo!"

And when Luigi had woken up and seen Mario? Safe and sound in the lab with him? Gooigi was sure he would never feel so much joy from another person ever again.

It was so alien to Gooigi how quickly Luigi's emotions could explode outward like that. Though most people were hard to read for him, Gooigi was learning from watching Luigi what faces people naturally make in reference to certain emotions. It also helped that when Gooigi was in his tank on the Poltergust, he could see through the eyes of whoever was wearing the tank, which was always Luigi. Mario wore it once, but Gooigi wasn't in the tank at the time. Whenever Luigi went through something that made his emotions explode, Gooigi could feel all of it from his tank, and it was overwhelming, each emotion striking him like a bucket of cold water, to the point where he tried to stay out of the tank as much as possible so he could get a break from that. He couldn't even sleep when Luigi would flinch at every tiny noise, his fear spiking enough to hurt him every time.

"Stop." Luigi lifted a hand, halting the other two in their tracks, "I don't like this. It's too cold and quiet."

Mario grasped Luigi's left hand, giving him a subtle nod. He hadn't realized his hands were shaking.

Luigi took a deep breath, letting it out with a huff, "Okay. Slowly."

Three beams of light descended onto the worn, faded carpet as the three of them made their way into the room. Gooigi could see further into the darkness than he knew the other two could, so he used that to look for anything that might jump out at them without any warning. Specifically, he was looking for those shadows that indicated something hidden, which meant they could reveal it with the dark light.

It was about halfway through the large room that he heard it; A very faint click.

Gooigi put an arm in front of Luigi to stop him.

"What? What's wrong?"

Both brothers' had turned on him. Did they not hear it?

 _Communicate._ He reminded himself, _They can't understand you if you don't communicate what you're feeling._

He thought for a minute before he placed a hand around his ear.

Luigi considered the gesture, "You heard something?"

Gooigi nodded.

"What do you hear?"

He didn't reply. He simply looked around for what could have made the sound.

Luigi took the time to search the room more thoroughly with his flashlight. The dark light swept over the walls, and when an object was revealed, he would quickly suck up the illusion orbs with the vacuum. Gooigi watched him for a few moments before joining him, though the fact that he hadn't heard another click was worrying.

It wasn't until they got to the other side of the room when a ghost appeared through the door.

"AAAAAAAAAIII!!!" Luigi jumped backwards, hitting his head on the floor.

"Luigi!" Mario helped him stand.

"I'm fine!" he panted as he stood up, "Remember what I told you!"

"Yeah!"

Luigi and Gooigi were used to this by now. They had been doing this together for at least a few hours at this point, and now that Luigi was well-rested, he was alert as ever. Gooigi couldn't believe the difference that just a few hours of sleep could do. If either brother started growing sluggish, he was sure it would be easier for him to notice now.

Once the last ghost was slammed into the ground, Luigi wiped the sweat from his brow, the gates on the doors lifting.

"Whoa!" Mario ran to his side, laughing, "That was amazing!"

Luigi blushed at the praise, scratching his head, "Eh, you know. All in a day's work."

The three of them headed towards the next door. If Luigi was remembering correctly, this door would lead to the final room on this floor. He reached for the doorknob.

It wouldn't move.

"Huh?" a cold feeling of dread settled in Luigi's fingertips, "It's...locked?"

Gooigi took the knob next, yanking and tugging on the knob to try and get it to move. It still wouldn't budge.

What was going on? This door wasn't supposed to be locked. Luigi took a step back.

"Luigi?" Mario reached for him, "Are you ok-!"

Another click was heard, and this time it was much louder.

Gooigi leapt forward, but it was too late.

"Ow!"

Luigi's eyes widened. He opened his mouth to scream, but no sound came out.

The click had come from a crossbow on what they thought was a broken statue. It had an arrow loaded, and it activated upon their arrival.

The arrow had gone straight through Mario's back, slipping between his ribs.

Luigi was frozen, his arms outstretched but stiff, his mouth still open. His thoughts had halted as if stuck in time, trapped in a loop of nothing. Gooigi wasn't sure who to be more worried about...until Mario fell and Luigi finally found his voice.

 _"MARIOOOOO!!!"_ He caught his brother, his gloves instantly soaked with blood, "No no no no no no no no! Mario! _Mario!"_

The faded carpet was soaked with red. Mario grasped one of Luigi's hands, but his grip was weak. The smell of blood made Luigi dizzy. Gooigi stood back, wanting to help but afraid of touching the dark liquid in case it made him melt.

Luigi tugged the arrow from Mario's chest, "No, I need...Gooigi, get me something..."

"Luigi." Mario said softly, "It's...it's okay..."

"No, no..." Luigi cried, "No, I can't lose you! Not now!"

"I'm sorry..." Mario gave Luigi's hand a squeeze before he lay back and closed his eyes.

"Don't!" Luigi watched his own tears fall on Mario's face, "Please! Don't leave me!"

Gooigi didn't like despair on Luigi. It didn't suit him. Sure, he didn't like Luigi being afraid either, but at least he still looked like himself. Luigi was very high-energy, that was clear, so seeing him like this...

Gooigi wracked his brain for anything he could do to help as Mario's chest deflated, seemingly for the last time. He knew he must be missing something, as in the back of his head, he swore he knew a situation like this. He'd thought about, and he knew Luigi had too.

What was he missing?

"N-no..." Luigi lifted Mario into his arms, "Don't leave me..."

Luigi was so tired. He didn't want to keep going. How could he go on like this, knowing he'd eventually have to go home and break the awful news? The idea of living in a world without him...

"Ah!" Gooigi tugged on Luigi's shoulders to sit him up.

"Ugh, what do you want?"

Gooigi ran to the nearby curtains, tearing them down and brushing the dust off as he carried them back he knelt by Mario's side, wrapping his torso and tying it tightly.

Luigi couldn't help but roll his eyes, "What are you _doing!?_ He's not breathing anymore! Get away from him! Can't you just let him _rest!?"_

Luigi tried to pry him away, but Gooigi wouldn't let him. He knew Mario was still alive, he could feel it, but he wouldn't be for long unless he did something to stop it. Finally, Gooigi was done tying the knot, and he turned to Luigi, shoving him as hard as he could so that he was forced to let go out of shock.

Once he was free, Gooigi ran off, calling out, _"Here here!"_ with his seldom-used, warbling voice. "Here!" was easy for him to say, because it was all vowels and no sharp consonants that could trip him up in pronunciation.

Luigi's patience was wearing thin, "Gooigi! What in the name of Luma's grand power star are you doing!? Are you trying to alert _all_ the ghosts to our presence!?"

 _Just one of them, you idiot!_ Gooigi tried to project his frustration into Luigi's mind, but they weren't connected when he was outside his tank.

"Gooigi, stop!"

He didn't.

"Gooigi!" Luigi grabbed his arms, _"Why can't you just tell me what you're doing!?"_

Gooigi could have easily just bent around Luigi's fists to break free, but he didn't. He was too stunned. Luigi wanted him to talk? But he didn't want to! And besides, if he didn't enact his plan fast, Mario would-!

"Just give it a rest." Luigi sobbed, "Pease."

Gooigi broke free at this point, running down the hallway until he was well out of Luigi's earshot. He wasn't followed. Good. Maybe now he could enact his plan in peace.

Luigi returned to Mario's side. He was beginning to pale, his skin slick with cold sweat. Sweat? Was Mario sweating before he died? He didn't remember.

Great. Now he'd lost Mario _and_ Gooigi. A few tears fell from his face onto the floor. 

What was he going to do?

He was shaken from his train of thought by the distant sounds of barking. Polterpup ran right past him, kissing Mario's face until color returned to it.

"Hey! What are you doing!?" Luigi tried to grab him, "Polterpup, down! _I said down!"_

He didn't notice Gooigi return with an odd device in his hands, and he didn't notice when Mario began to stir. He just put all his energy into trying to control Polterpup through a curtain of tears and resisting the urge to scream.

"Please! Just leave him alone!" something inside him snapped like a broken guitar string, and he ended up collapsing into Polterpup's side and crying into his collar.

He didn't know how long he stayed like that, or when Polterpup started nuzzling under his chin to try and comfort him. All he knew next was the hum of electronics as arms wrapped around him, so familiar it made his heart lurch.

_"M-M-Mario?"_

The VB began to ring, and Luigi answered it stiffly.

_"Luigi, I'm bringing you back."_

***


	6. Chapter 6

Luigi hadn't spoken in twenty minutes. He alternated between hugging Mario and pacing around the room, pausing every now and then to rock back and forth on his heels, his hands twisting around each other until a thread on one glove came loose.

Gooigi tried to determine what was going through Luigi's head, but for once, he had made himself difficult to read. Considering what had happened, though...he had a few guesses.

E. Gadd lifted his hands from his keyboard, "Luigi, you're not helping anyone."

Luigi stopped, a long sigh escaping him.

"Sorry..." he rubbed his arm, "I just can't stop thinking about..."

Mario leaned back against the wall of the lab, tapping his heel against the smooth metal.

Luigi dug his palms into his eyes, a shutter wracking his frame and raising goosebumps all over his skin.

E. Gadd leaned back in his chair, checking the map on his main monitor, "Don't worry. Your princess will be fine for a little longer."

"That's not what I'm worried about."

Gooigi wasn't sure what kind of atmosphere hung in the air among all of them, but he did know that he didn't like it.

"Gooigi, please tell me what you did." Luigi whirled on him, "I'm sorry for yelling at you, but I thought he was dead. I was sure of it! Why..."

"Luigi." E. Gadd gestured to the device still stuck to Mario's chest under his shirt, just visible through the hole the arrow had left behind, "That thing is intended to stop blood from leaving a wound, and it uses nanobots to do basic tissue repair. I created it in college, back when I was still sane. Gooigi knew I had it, so he used something else to stifle the blood until he could get it."

"Then why did he call out to Polterpup?"

"Well, haven't you ever wondered why he's always there when you fall in battle? It's because Polterpup has the ability to reverse the effects of injuries and stress. It's not perfect, but it has saved your life many times, my boy."

Luigi was trembling again. It wasn't the first time he'd been traumatized, but the image of Mario's body, white as a sheet, lying in a pool of blood made him remember just how awful it was every time it happened.

"Gooigi..." Luigi covered his mouth as he stared at the gooy figure in question, "You saved his life..."

Gooigi looked at the floor. He hated being stared at. He hated being scrutinized like this.

Still. Luigi seemed to be begging the question. If someone in their party came that close to death, how much longer could they last before their luck ran out?

Luigi took his cap off to run a hand through his hair, "What if we don't ever make it to Peach?"

Gooigi reached out, hesitated, then placed a hand on Luigi's shoulder.

Luigi looked up into those blank, pupil-less eyes. The glow from the various monitors in the room almost made them look glossy white, as the goo reflected it back almost perfectly. It was chilling, in a way. Like the eyes of a ghost.

Gooigi lifted his hand, then brought it down again. He did this a few times.

"Are you..." Luigi took the gooy hand that had been giving him pats, "...trying to comfort me?"

Gooigi thought for a moment, then he nodded.

"Oh." Luigi stared down at the floor, "Thank you."

The sound of the fan in the room was too loud.

"Well..." E. Gadd adjusted his glasses, "If you can't find the key to the last room, then maybe you should check the other rooms you haven't been in yet. Who knows? The princess might be in one of them."

Luigi gave a slow nod, "Yeah. Okay."

Mario took him in a side-hug, "Do you need to rest?"

"No no, I'm fine." Luigi massaged his temples, "Just a bit of a headache."

The three of them left the lab in low spirits. Mario glanced back at E. Gadd before the door separated them.

"Okay. Tell me if it gets any worse."

The elevator ride up was tense. Luigi's mind was going through all manner of worst-case scenarios, unhelpfully cycling between anger at King Boo and guilt for almost losing the one person he cared about more than anything else. Why? Why did it have to be Mario? Why did it have to be King Boo? Why was it always Luigi's job to get rid of him!? Why couldn't Luigi fight something he wasn't so deathly afraid of!? He didn't notice the tears pouring down his face until Mario gave his shaking hand another squeeze.

Luigi gasped, visual snow clearing at the oxygen the action brought.

"Luigi, it's okay." Mario said, "It's going to be okay."

Luigi loosened his death grip on the flashlight in his right hand, "S-sorry. I dunno why I'm so..."

Gooigi stood by his other side, a gentle hand on his arm.

"Don't apologize." Mario moved so he was further within Luigi's line of sight, "You just went through something awful. It's only natural you'd be on edge."

Luigi swallowed, "I just...why am I so afraid? You aren't afraid of anything."

"That's wrong." Mario replied immediately, "I'm afraid of a lot of things. I'm just better at hiding it than you are, and besides, I think we can agree that I'm a little bit of a thrill-seeker."

Luigi didn't seem convinced, so he added;

"I'm afraid of losing you."

Luigi exhaled, "I hate this. I hate being afraid."

"I know you do."

The elevator stopped, and the doors opened.

The first thing Gooigi noticed was the fact that it was too dark to see. The mist that poured in from outside didn't help, in fact as it washed over the floor, he could clearly make out that it was black, even with his limited color perception.

Luigi coughed, "Oh boy. Gooigi?"

He got the hint, beginning to vacuum up the thick smoke blocking their path. As the hallway became more discernible with their combined efforts, the source of the smoke became apparent. There was a giant bonfire in the center of the main room. Though the fire burned hot and bright, glowing a ghostly blue color, it wasn't spreading to the rest of the building, or even to the surrounding carpet. In fact, if Gooigi looked closely, he could have sworn the fire wasn't actually burning anything at all.

The heat washed over his face, and he staggered backwards, stumbling.

"Gooigi?" Luigi placed two fingers to his ear, "Mario, Gooigi can't go near the fire or he'll melt. He needs to stay here."

Gooigi reached for Luigi, just grasping the back of the Poltergust before he was out of reach.

"It's okay, Gooigi. I'm sure there's a way to put that fire out."

Gooigi didn't let go. He tugged harder.

"Gooigi, it's fine. Really. We'll be back before you even miss us."

Gooigi gave a few more insistent tugs, gurgling in a way that almost sounded like a cry for help. A worried warble. His legs jiggled back and forth like a shaken plate of jello salad. His grip was flimsy, but he only held tighter. He refused to let Luigi go.

"Whoa, hey." Luigi dropped his flashlight as he grabbed Gooigi's arms to steady him, "Gooigi, what's wrong?"

Gooigi looked back at the fire, then he tugged on Luigi again, though not as desperately now that he had his attention.

Luigi scrutinized the strange goo creature. Shaking limbs, a desire to run, eyebrows drawn into a subtle approximation of a grimace.

"Gooigi..." he said, "Are you afraid?"

Gooigi's gaze darted between him and the fire. He was quiet for a long time, but eventually, he nodded.

Luigi's heart melted. There wasn't a sliver of doubt left in his mind; Gooigi was not only alive, but sentient. He had complex thought processes and emotions. He was capable of higher reasoning and logic. He was basically human, albeit a little less solid.

Luigi led his two partners back towards the elevator when the smoke returned, "Are you afraid for my safety?"

Gooigi looked at the ground. Then he nodded.

"Oh no..." Luigi hit his face with the palm of his hand, "Gooigi, I'm so sorry. I've treated you so poorly all this time. Nobody deserves that. I'm sorry."

Gooigi shook his head, waving his hand dismissively.

Luigi laughed humorlessly, "Thanks, but I still feel bad. I didn't realize you even cared about me."

Gooigi responded in a way Luigi wasn't expecting; He lifted his arms and wrapped them around Luigi's torso in a soft, gooy hug.

He couldn't help but get a little choked up at that. He returned the hug, his arms around his shoulders.

"Thank you. I mean it." Luigi pulled away, "Listen, Gooigi; I promise I'll be okay. You can trust me. Me and Mario will be in and out before you know it, alright?"

Gooigi shook his head, his grip tightening.

"Gooigi." Luigi forced those blank eyes to look up into his, "I swear to you. I will come back safe and sound."

Gooigi's eyebrows creased in distress, the closest he could get to a real facial expression.

"Gooigi." Luigi's voice became more stern, _"Gooigi,_ let go of me. I'm coming back. I promise."

Gooigi finally conceded, his arms falling as he stepped backwards towards the elevator.

"Cool." Luigi returned to vacuuming the air, "Come on, Mario!"

"Okay!"

Gooigi watched them go, feeling as though there was goo missing in his stomach. A heavy weight, maybe. A solid block of dread.

He held the vacuum in one hand, the other wrapped around himself as he studied the pattern on the carpet, distracting himself from this new emotion he couldn't blame on anyone else.

***


	7. Chapter 7

Luigi coughed a few times into his sleeve before he finally tugged the collar of his shirt up to cover his nose and mouth, "Stay close to me!"

Mario held his flashlight in his left hand so he could hold Luigi's, also trying to shield his face with his shirt collar. The smoke wasn't too thick near the ground, thankfully, but it was impossible to see through, and it was burning his lungs and making his eyes water. He removed the cloth on his face to cough again.

"Mario, hold this for me!" he handed the nozzle of the vacuum over, still on, before replacing the makeshift mask, "I don't think this room is ventilated at all! Do you see a window anywhere?"

Mario reached out until he found the wall, guiding his brother along it until he found an indentation of smooth glass. It was cracked, however. Mario brought Luigi's hand to it, carefully avoiding the cracks.

"Aha!" Luigi took the vacuum back and swung it into the glass, breaking the window and allowing smoke to pour out. A gust of wind hit him in the face, and he took a grateful gulp of fresh air. He turned to where he knew Mario was, just catching him leaning out the window for more of that precious oxygen.

He tried to see into the room through the smoke, where the cold air was pushing back against the fire. It gave him his first glimpse of the ceiling, and it was lined with sprinklers, though the system clearly hadn't activated with the smoke. Now that he had access to more oxygen, he could think more clearly, and seeing the sprinklers clearly deactivated gave him an idea.

"Let's go back." he took Mario's hand, "There are sprinklers on the ceiling I think we can turn on, but we have to warn Gooigi or he'll melt in the water. How's your wound?"

Mario steeled himself, re-covering his face before he said, "Fine. Let's go."

As they approached the elevator, the two vacuums did a much better job of clearing the smoke than one, so Gooigi spotted them further away than he would have otherwise.

Luigi shouted over the roaring flames, "Gooigi! There are sprinklers on the ceiling!"

Gooigi recognized the words, connected them to meaning, and then shook his head.

Luigi got to his side, grateful for a break from dealing with the fire, "You need to stand inside the elevator...or if you return to the tank you can come with us, but we won't be able to clear the smoke as efficiently that way."

Gooigi considered the conundrum for a long time. Luigi was learning that he had some delay in processing, so he patiently waited for any possible response.

Finally, Gooigi stepped back into the elevator, his vacuum still on.

"Okay! We'll be back!" Luigi let the smoke clear before venturing back into the darkness.

He hugged the wall to look for hallways or sprinkler pipes or wires that could indicate some direction. Mario still had his flashlight, so they could see a little bit, but for the most part they had to guess where they were going. Luigi's fingers found a corner that turned outward, so he followed it, keeping his eyes closed for the most part since they were stinging and they couldn't see through the smoke anyway. His touch landed on something metallic, and he flinched away from it when it lightly shocked him.

He opened his eyes to see what he had touched. It was a frayed wire connected to a fuse box. The fuses were intact, but there was no power. Most importantly though, it had three dark green circles on it, placed far enough away from each other that they could all be hit by a charged strobulb.

"Mario!" Luigi followed the beam of the flashlight to the vague form of his brother behind him, "We need to hit these with the strobulb!"

That would be impossible, he quickly realized. If he was more than two feet away from the fusebox, it disappeared behind the thick smoke. The bulb needed clearer air than this to work.

 _"Luigi!"_ he jumped at the voice of E. Gadd in his ear, _"You won't last much longer in there! You need to find a better way to clear the smoke!"_

Luigi shivered despite the sweat clinging to his hair, "How do I do that!?"

_"I don't know! Is there a window!? A vent!? An oxygen tank!? It's too late to go back before you pass out, so be resourceful! Get creative!"_

Luigi took his hat off so he could wipe his forehead. Reaching back to take Mario's wrist before he could run off, he kept his vacuum pointed at the wall, searching for a doorway or a window. His vision was blacking out. His ears were ringing. He resisted the urge to gasp as his lungs protested the shallow breaths he took. He knew he only had seconds left to find some semblance of safety, but he couldn't think clearly anymore. He felt like he was drowning. His coughs got more frequent. He couldn't breathe. He was in pain. He could feel himself falling-!

In his panic-inducing state, he didn't notice at first the firm arms that wrapped around him and dragged him away. When he did, he weakly tried to fight it, his irritated eyes brimming with tears. For all he knew, he had been found by a snatcher and was on his way to that lovely picture frame with his name carved into it.

He was so scared that he didn't notice when he was laid down and the fog in his head began to clear. A hand gently wiped his tears away, prompting him to open his eyes.

Luigi was on his back on the floor, in a room he didn't recognize. Mario was hovering over him, his eyes red and raw from the smoke, coughing into his sleeve to dispel the remaining irritants. His eyes met Luigi's, and he wrapped an arm around him, helping him sit up.

"Are you okay?"

Luigi had never been so happy just to have access to clean air. He took many deep breaths, his sore throat soothed by the rush of wind from the window in the back wall. He let out a choked sob, throwing his arms around his brother like something might take him away at any moment.

 _"I'm sorry..."_ he said softly, _"I don't know what came over me, I'm sorry..."_

"It's okay, Luigi."

_"I fought against you."_

"I know you did."

_"You saved me."_

"Of course."

_"I'm sorry."_

"It's not your fault."

Mario helped him stand up, and he took a moment to survey the room. The door they had come from had a small window in it, but of course it was completely black. The room was actually fairly bright because the window faced the moon, and because the window was open, any smoke that could have been in the room was vented out.

Of course, there was only one exit if they didn't want to fall to their death. They couldn't stay forever.

Luigi swallowed, his voice coming out a little hoarse, "Mario, we need to find a way to vent all this smoke. It's too thick to use the strobulb, even if we use a charged shot."

Mario moved to the window on the door, where the Polter G-00 and spare flashlight were leaning against the wall, "Maybe if we find more rooms to open up, the smoke will be able to escape."

"Good thinking, but what if there aren't any more rooms?"

Mario swept up the Poltergust, reaching for the doorknob.

"Hey, Mario." Luigi snatched his arm, "Be careful. The Poltergust is heavy enough to limit your actions."

"Got it!"

Mario closed the door behind him, making Luigi roll his eyes and mutter, _"Oh, please."_ before he opened the door wide open, spilling smoke into the room and out the window. He let the smoke vent for a minute or so before glancing back into the hallway, which was clear enough now that the opposite wall of the hallway was visible. Luigi picked up the flashlight before propping the door open with one of the tall trash cans and heading out. Some other doors were now visible, so Luigi entered each one, looking for windows he could open and furniture to keep doors open with until the hallway was clear enough to see, although breathing was still a bit of a challenge.

He found Mario in the third room he checked, noticing that the rest of the doors in the hallway were propped open.

"Lui-!" Mario coughed, "Luigi, are you okay?"

"I'm fine." Luigi charged up his flashlight, "Close your eyes."

He did, so Luigi aimed and fired, flinching back against the light. The fusebox lit up with electricity, and with a loud clattering noise, the sprinklers sprang to life, drenching the entire floor with raining water.

The two of them headed back towards the main room, shielding their faces from the onslaught, until they made it back to the fire, which had completely gone out, revealing a scorched picture frame in the middle of the pile of charred furniture.

"Gooigi!" Luigi slipped on the water, falling to his elbows before scrambling back up. The elevator doors were closed. Once the sprinklers finally shut off, Luigi hit the elevator button.

The elevator opened, and there was Gooigi, as blank as ever.

"Whew." Luigi took his cap off to push his wet hair off his forehead, squeezing the water out of it in a tight fist, "I told you I would be fine."

Gooigi glanced over Luigi's shoulder as he replaced the cap.

"Yeah, Mario's here too." he followed Gooigi's line of sight, "He probably saw the..."

The painting.

Princess Peach's painting.

Mario set the frame down, and Luigi wasted no time hitting it with the dark light. Golden blonde hair atop a flushed face and pink dress. Mario caught her hands before she had a chance to stumble.

"Mario!" she hugged him tightly.

"Peach!" he replied gleefully, "Ouch!"

"Sorry! I didn't realize you were injured!"

As soon as she turned away from him, Luigi threw himself at her, "Princess!"

"Luigi!" she gave him a hearty squeeze, "I'm so happy to see you! Are you okay? You're not hurt?"

Luigi laughed, "No, I'm fine. Are you?"

"I'm okay!" Peach wiped her tears away, "Oh, you boys must tell me what happened! I didn't even see what attacked me!"

Luigi took her hand to guide her to the elevator, "Don't worry. We have a base of operations. Let's head back there."

Peach paused once inside, her eyes falling on Gooigi. Luigi got the elevator moving before he noticed her hesitation.

"Oh, you haven't met him yet, have you?" Luigi made sure his hand was dry before pushing him forward, "Princess, this is Gooigi. Gooigi, this is Princess Peach."

"Oh." Peach smiled at him, "Nice to meet you, Gooigi!"

Gooigi took her hand and held it the way Luigi had, tilting his head at it curiously.

Luigi gently hit his shoulder, which rebounded the way goo does, "Be patient with him. He's still learning."

***


	8. Chapter 8

"So that's it, then!" E. Gadd spun his chair around, "We can go now! You've saved all your friends!"

Luigi cringed, "Um...I guess, but won't this problem continue if King Boo is left to roam free?"

"Ugh!" E. Gadd slid down until his legs dangled from his seat, "Can't we just make a run for it? He can't catch _all_ of us!"

Luigi rubbed his temples with a thumb and forefinger, "E. Gadd..."

"What? Can you blame an old man for wanting to stay out of danger?"

"He's just going to follow us."

"Both of you, be quiet." Peach said gently, "Who's to say King Boo would even let us go?"

The silence was punctuated by Gooigi's tapping foot.

"Well, we should at least get Peach to safety." Luigi decided, "I can get the boards off the front door and fix up the bus and all the toads can head out-!"

"What? No!" Peach crossed her arms, "I can't just leave you here!"

"But what if you get hurt!?"

"But what about _you!?"_

Luigi frowned, letting himself deflate slightly.

"Princess, please." Luigi took both her hands in his own, "I would never forgive myself if anything happened to you."

Peach leaned towards him slightly, "Luigi. I know you're concerned for my safety, but how do you think _I_ feel? I'd do nothing but worry."

"Princess, I can't..."

"I'm not leaving without all of you."

"Princess-!"

"I'm not leaving!"

_"Peach!"_

Her mouth snapped shut.

"I already almost lost Mario..." Luigi bit his lip, "I don't know what I'd do if I lost you."

"Luigi..." Peach slowly reached out to brush a stray hair from Luigi's face, "You know I can take care of myself. Besides, I have you three to protect me, don't I?"

Luigi glanced at the door of the lab, considering the idea of simply abandoning ship and dealing with that stupid boo later.

"Alright. You can come with us."

"Thank you."

"But you need to promise that you'll keep yourself safe. Only Gooigi is allowed to separate from us. The rest of us will stick together no matter what, alright?"

"Okay!"

"Good." Luigi emptied the Poltergust into the vault before heading outside, his friends not far behind, "Then let's go."

***

Luigi decided to return to the floor with the bonfire on it. The doors opened, and Luigi's gaze immediately went to the ceiling. It was totally blackened, giving it the appearance of a void that went on forever. It kind of creeped him out to think that the byproduct of that fire had gotten into his lungs.

"Yeesh." Mario was the last off the elevator before it closed, "Why'd you bring us back here?"

"Because without the smoke, it'll be much easier to explore." Luigi shone his flashlight across the floor, "The key to that door might be here, or something else that proves useful."

Gooigi lagged behind as he stared at the wreckage, carefully maneuvering around the puddles that were left behind by the sprinklers. Something was giving him an uneasy feeling, and it wasn't just the drips that came from the ceiling. It got so bad that Gooigi halted Luigi in his tracks while continuing to search for the source of the feeling.

"Gooigi? Is something wrong?" Luigi said, a little panicked, "Do you hear something?"

Gooigi shook his head.

"What's up, then?"

Gooigi didn't reply.

"Okay. We might be looking for a fight." Luigi lifted his arm in an attempt to shield Mario and Peach, "Watch out."

Gooigi stood on the other side of their group, his gooy Poltergust at the ready. The feeling descended on him until it made his body ripple, a fog drifting over his thoughts and making him huddle closer to his companions as he feared losing consciousness.

Then the feeling snapped like a rubber band, and his gaze hit the floor.

He cried out in what he hoped could be interpreted as a warning before he was swallowed up by another blob of goo.

"Gooigi!" Luigi flashed the strobulb just in time to see a purple ghost emerge from the ground, tall enough that it wouldn't have fit into the elevator.

It reared its body at the flash, a glowing smile taking over the blob on top of its body that could count as a head. Most importantly though, it had smaller blobs of green goo inside its body, flowing around in droplets like a frenetic lava lamp.

"Oh no!" Mario grabbed Luigi's overall straps to yank him away from the goo monster's attack.

"Ack!" Luigi forced his frozen limbs to move, "Gooigi isn't returning to the tank! He must be trapped!"

Peach hovered behind the two brothers, "What do we do!?"

Luigi turned on the dark light, the strobulb, the vacuum, but nothing seemed to phase it. He tried to recall what he knew about goo. Fire and water would melt it obviously, but he didn't want to risk hurting Gooigi. Maybe if he broke it apart, it would be easier to target the smaller blobs, but what could he break it with?

"Mario! Princess! Follow me!"

He ran across the room to search for something that wouldn't immediately get sucked into the Poltergust, urging Mario and Peach ahead of him so he could watch over them as he looked around. He finally settled on a cooled coal from the recently-snuffed fire, sucking it up and waiting for the monster to get close enough before letting it fly.

The goo monster exploded into smaller monsters, a few of the green blobs becoming dislodged and returning to the tank on Luigi's back. At least some of Gooigi was safe. Luigi vacuumed up the smaller goo monsters easily while bigger ones needed a flash to stun them first. They had a tendency to clump back together of course, so more coals were needed to keep breaking them apart, freeing more of Gooigi and splitting the monster into smaller and smaller pieces until every last drop of green was back in the tank.

"That's it!" Luigi bolted down the hall to hit the sprinklers, and the purple goo monster was no more.

Nobody moved until the goo had washed away, the sprinklers stopped, and a golden key was spat out. The lights came on as Luigi re-emerged from the hallway.

"Wahoo!" Mario cheered, "Luigi number one!"

"Ho ho!" Luigi hit Mario's hand in a high-five, "Luigi number one!"

"That was amazing, Luigi!" Peach twisted her hair to expel the water, "I don't think I've ever seen you move like that!"

"Ah well, you know..." Luigi blushed under the praise, "All in a day's work. Now let's see about that key."

***

Luigi set the Poltergust down once they were back inside the elevator, "Gooigi? Are you okay?"

Gooigi only barely heard him. His head was swimming like a fishbowl. When he did finally connect Luigi's words to meaning, Luigi had started speaking again.

"Here, come out, okay?" Luigi hit the button that would summon him.

Gooigi got that message clearly, at least. As soon as he felt the tug, he emerged in a puddle and began to reform.

It didn't come very easily, however, and that was clear from the outside. He only formed up to his arms at first, his goo feeling so much heavier than he was used to. He climbed out of his puddle by dragging his body across the ground, attempting to stand once his legs had formed. Luigi caught him when they collapsed under his weight.

"Whoa! Gooigi!" Luigi sat him up, "What's wrong? Are you in pain?"

Gooigi didn't reply. He didn't want to move.

Peach gasped, "Luigi, look!"

He did. Inside where Gooigi's ribcage would be was a tiny purple blob no bigger than a grape. Gooigi placed a hand to his chest, quivering at the unnatural sensation. It didn't feel as if the blob was directly hurting him, it was just the fact that his own goo should be there, filling that space, but it _wasn't there-!_

"We'd better get him back to E. Gadd." Luigi stood to hit the button for the basement.

The lurch made Gooigi's head spin. He fell backwards so he was lying down, the jostling from the elevator only adding to the head-underwater feeling. Luigi knelt beside him, taking Gooigi's head in his hand and looking into glassy eyes that he once thought had no true intelligence behind them. How had it taken as long as it did before he realized how wrong he was?

E. Gadd was out of his chair before the lab door opened, "Luigi! I lost contact with you for a bit there! What's going on!?"

Luigi was walking with Gooigi's arm around his shoulders to hold him upright.

"Oh dear..." E. Gadd returned to his chair, "I see Gooigi has an unwelcome guest. Gooigi, recall."

Gooigi didn't hear him. He cocked his head in confusion, letting out a distressed warble.

"Gooigi, I can help you, but you need to cooperate! Did you hear what I said? _Recall!"_

It took Gooigi another minute to understand, but once he did, he sluggishly disintegrated to return to the Poltergust's tank.

"Okay, Luigi. Turn around."

Luigi turned his back to E. Gadd, who detached the tank from the Poltergust. Setting it upright on the desk, he checked the measurement lines along the side. Gooigi in his disintegrated liquid form was almost exactly 1,000 milliliters, so E. Gadd designed the tank to hold about 500 more than that to account for a situation like this. Reading the measures, his fear was confirmed; The liquid went beyond the 1,000 marker.

"Okay, it looks like that foreign goo is sticking to Gooigi, so I'll need to remove it manually." E. Gadd twisted the top of the tank off and retrieved an eye dropper, "This won't take long."

Gooigi braced for the eye dropper. It sunk into the gooy liquid, searching carefully for the offending spot. It felt as if something was stretching the membrane of his cells, like an object was going straight through flesh to meddle with organs. He hated it so much that he shuttered away from the tool, taking the spot with him.

"I know. This isn't very comfortable for you, is it?" E. Gadd soothed, "Just try to relax, okay? As soon as I get that thing out, you'll feel much better. I promise."

He tried to comply, holding the spot still so E. Gadd could properly aim the eye dropper. As soon as he was aligned, he sucked up the spot and pulled it out. The fog instantly cleared. Even before the tool was out, he felt much better.

"Perfect!" E. Gadd set the tool down, checking the measurement lines again. Exactly 1,000 milliliters, as it should be. He screwed the top of the tank back on, "Luigi?"

Once the tank was reattached to the Poltergust, Luigi said, "Gooigi? Can you hear me? Are you alright?"

Gooigi emerged and reformed. He pat himself down, almost to make sure the pain wouldn't return, then he gave a thumbs up.

Mario looked at the eyedropper on the desk, still containing that tiny blob of purple goo, "What happened?"

E. Gadd turned his monitor on, "Goo isn't chemically inert. It reacts with other chemicals, including other types of goo. When another living goo reacted with Gooigi, his body became stickier, which protected him from the foreign invader, but it also makes Gooigi worse at holding his form as well as changing forms. On top of that, being in contact with another type of goo means their frequencies will clash, which is very painful for them."

Luigi had a hand stroking his chin as he realized that he didn't even know what goo was made of. It had some properties of regular ghosts, yet it also had physical properties too. Gooigi couldn't phase through walls, for example.

"Curious?" E. Gadd got a spark in his eye, "Goo is a ghostly chemical, Luigi. after all, how can apparitions of peoples' dying wishes gain the ability to interact with those of us who still have our physical bodies?"

"Oh..." Luigi glanced at Gooigi, who was holding his translucent arm up to the light, "Oh!"

"Yep. Gooigi is almost entirely made out of ectoplasm I've collected from ghosts! You don't even have to hurt them to get a sample, so I basically recruited a bunch of friendly greenies to give me samples until I had enough to bring to life like a proverbial Frankenstein's Monster!"

Peach grimaced in disgust, "You do know how that book goes, right?"

E. Gadd's unsettling laughter died down, "Actually, that book doesn't go well, does it? Scratch that, not like Frankenstein's Monster. The point is, goo is extraordinarily fascinating, and Gooigi is not only the result of my research, but he's also given me valuable insight into how goo works."

Gooigi finished looking himself over before he visibly shuttered, air gurgling through him like a sigh of relief.

"He's a little bit like my son." E. Gadd chuckled, "Now, try not to trifle with goo again, alright Gooigi?

Gooigi nodded.

"Well then! That's that!" E. Gadd picked up the dropper, "I'll add this to my specimens. In the meantime, you have a key, do you not?"

***

**Notes for the Chapter:**

> By the way, if anyone is picking up on subtle hints of Luigi/Peach, that's because I kind of low-key ship them and can't help myself. I left it out enough to not have to tag it, but I bet it'll show up again in another story.


	9. Chapter 9

Luigi stood in front of the locked door, searching his pockets for the key, "Okay. Let's hope this works."

He slid the key into the lock...

But it wouldn't twist.

"Ugh! Come on!" Luigi tried to force it, bracing against the wall to yank and shove it, but it wouldn't budge.

"Stop! You'll break it!" Peach pulled him from the door, “Maybe this key is for a different door.”

“I don’t understand! I thought all the doors had the same lock...” Luigi hit his forehead on the door, his hat flying to the ground, “Why can’t this just be over already...”

Mario put a hand on his shoulder. Luigi lifted his head, taking the key from the lock and numbly stashing it, his gaze landing on his hat as he turned away from the door.

"Luigi?" Mario said, "Are you okay?"

Luigi ran a fist over his eyes, taking a huge breath of air and letting it out slowly.

_"No, not really."_

Mario lifted his arms in an offer for a hug, and Luigi accepted it gratefully.

Peach stooped to pick up Luigi’s hat, placing it gingerly over his head. Luigi adjusted it as he pulled away from Mario, his eyes hidden beneath its shadow.

"I'm so tired." Luigi slumped, "I just want to go home."

"Me too." Mario headed back towards the door, "Maybe we should take a break. You look like you might fall asleep standing up."

"No no, I'm..." he was going to say he was fine, but that wasn't exactly true, "I can keep going."

"Are you sure?"

"Yeah." Luigi swept his flashlight over the walls, "Well, we do know that there's another room we haven't been to yet, so let's head there."

One elevator ride later, and they were in a new room with a single door. Attempting to open the door revealed that it was locked. Luigi put the key in the lock, and it unlocked easily. The key disappeared inside the lock, and Luigi was still baffled every time it happened even now. He didn't dwell on it, though. He was just happy this key wasn't going to waste.

Pushing the door open, he waited for his companions to rejoin him before sweeping the flashlight across the room. It was pitch-black, with no windows and broken lights. The three flashlight beams were the only source of light. The first thing that struck Luigi about this room is that it was clearly once a bedroom. A fancy bed with a canopy and thick sheets, a dresser and wardrobe housing many fancy dresses, hats, stockings and shoes. The second thing he noticed was that it was almost entirely green. In fact, if Luigi was being crazy, he could have sworn that the wallpaper and bedsheets were glowing with that mesmerizing neon color. If it wasn't so faded from age, it might have been blinding despite the darkness.

The door shut behind them, and Luigi gave a sigh, "Alright. So, what now?"

Gooigi touched the wallpaper, then he recoiled as if he'd been burned.

Luigi's earpiece dinged, _"Luigi! Don't touch anything in that room!"_

"Huh?" Luigi inspected the wallpaper, "Why?"

_"Because it's full of arsenic!"_

"Arsenic!?" Luigi tugged Gooigi away from the wall, "Why arsenic!?"

_"People didn't know it was dangerous back in the day! It makes a beautiful green color! You can't stay in there!"_

Luigi couldn't believe what he was looking at. Everything in the room was green to the point where Gooigi was almost camouflaged out of sight, "I don't understand. This hotel isn't that old!"

E. Gadd didn't reply, though the faint sounds of a keyboard could be heard in the background before his mic cut off.

Gooigi garbled as he yanked open the door and ushered the other three towards it.

"Wait! We can't just leave!" Luigi headed further in, "This could be our only chance! If we don't find anything in here, King Boo will come back later and make everything worse!"

Gooigi decided to keep the door open just to be safe, and the four of them cautiously began to explore.

Luigi did make an effort to not directly touch things. He clicked the flashlight off to hook the edge of the bulb around drawer handles and curtains. When he couldn't get a grip on something that way, he would dig a handkerchief out of his pocket to shield his glove from anything that could have traces of arsenic on them.

Peach warily eyed the melting wallpaper in the corner, "Why is there a Victorian room in a relatively modern hotel?"

"I've seen stranger in my adventures. I'm numb to it at this point." Luigi took a step and his arms windmilled when he lost his balance, _"Oohhh..."_

"Luigi?" Mario rushed to his side, "What's wrong?"

"I just..." Luigi blinked drowsily, "...feel light-headed all of a sudden..."

Mario placed a hand to Luigi's forehead, "We need to get you out of this room."

Luigi put up no resistance as Mario guided him out of the room, his breathing labored and his feet stumbling over themselves. He was beginning to lose feeling in his fingers and toes, at least until the door shut behind them as they entered the hallway.

"Are you okay, Luigi?" Peach stroked his temple with her thumb.

Her cool touch was soothing on his hot, sweaty skin, "Yeah, I'm fine. I'll be fine."

He swallowed around the sore lump in his throat, his headache worse than ever. He flexed his fingers, trying to dispel the tingly feeling that had settled in them.

"Here. Sit down." Mario led him to the wall.

Luigi took the Poltergust off to sit with his back to the wall, leaning his side against the vacuum. The air out in the main room was much more breathable, something he hadn't noticed when he was actually searching.

Gooigi knelt in front of him, lifting the brim of Luigi's hat to get a better look at him. He noted the flushed cheeks and forehead, the dark circles under his eyes, the thin sheen of sweat and the way he seemed to be shivering. This isn't what Luigi had looked like when Gooigi had first met him, nor was it how he had looked in the various photographs he’d been shown by E. Gadd. He’d been slowly deteriorating the longer he stayed here, and it astounded Gooigi that he had missed so many telltale signs of his stress and exhaustion, even with his limited knowledge on the world and on people.

"I'm fine, Gooigi." Luigi readjusted his cap, "Please. Don't stare at me like that."

Gooigi's gaze dropped to the floor, mumbling a warbly apology.

Mario looked over Luigi for any signs of injury, but he seemed mostly unharmed, just tired. When Luigi felt he could breathe normally again, he sat up, rubbing his eyes with the back of his fists.

"Okay, let's go back in."

"No!" Mario pushed him down when he tried to stand up, "I'm not letting you go back in there like this!"

"But I can't just sit around out here!"

Mario threw his hands up in exasperation, "I feel fine. I'm going in myself."

Luigi was frozen in place until Mario's hand was on the doorknob, feeling something cold shoot up from his stomach to his chest.

"NO!" Luigi launched himself at him, yanking the door closed, "Don't! Please! We can't get separated! Don't leave me out here!"

Mario quickly hugged him, "I'm sorry, Luigi. I'm right here. I'm not going anywhere."

Luigi's heart pounded in his ears like a drum. He clung to his brother like a lifeline, shaking with quiet sobs, though he was drained of tears. He felt a burning sensation sneak up his throat, and he pushed Mario away to dry-heave over the floor. He didn't know why, but his fight-or-flight response had been kicked into overdrive. The feeling of stickiness on his hands made him open his eyes, afraid he had hurt himself, but there was no blood. Just a shadow of a memory of holding the form of his older twin brother. Not moving. Not breathing.

He heaved again, but this time he managed to hack up saliva and stomach acid, the smell of which made his sudden nausea even worse. His head throbbed. He was freezing cold from the sweat that made his clothing stick to him uncomfortably. Mario knelt beside him to rub circles into his back, his other hand brushing Luigi's bangs from his face.

"Uuuggghhhhh..." Luigi coughed, miserably hanging his head as he sat on the verge of collapse, "I feel like I could use a shower..."

Mario offered a ghost of a smile, "And a nap. I haven't seen you this tired since I saved you from Ghostly Galaxy."

"Very funny, bro." Luigi gave a gravelly laugh.

He felt bad allowing anyone to go into that room alone if even breathing the air around that green wallpaper could kill them, but they couldn't leave without the key.

"Gooigi." Luigi realized, "Gooigi, you don't need to breathe. You can go in there alone. Is there any place we haven't thought to look yet?"

Gooigi put a hand to his chin, a habit he'd picked up from Luigi to provide a form of feedback while still giving him time to process what had been said. As soon as he did, he lifted his pointer finger in epiphany, heading back through the door to keep searching.

Almost immediately, he made the mistake of touching the melting wallpaper. He hissed as he recoiled, the goo on his fingers sizzling like melting plastic. The melted goo hit the floor, reformed, and then returned to his hand, leaving no scar behind.

"Are you okay?" Peach called in after him.

He gave a thumbs up before proceeding again, more cautiously this time. He didn't understand. Ghosts weren't hurt by poison as far as he knew. What kind of chemical reaction between goo and arsenic made this happen?

A smell of failed electrical wiring lingered in the air after he burned himself, probably because ectoplasmic material smelled like copper. If he was being crazy though, he also smelled something that reminded him of coffee. Was goo made of ectoplasm and coffee? That didn't make a lot of sense, but then again E. Gadd had a bad habit of leaving his coffee mugs too close to the edge of the table, so on top of his one-track mind, that could leave him prone to accidents. His question then was...if arsenic burned him, then what on earth did it do to people?

Nevermind that. He pushed the thought away as he opened one final drawer in the bench at the foot of the bed. Inside was a key.

 _"Ho ho!"_ Gooigi picked it up and quickly left the room, shivering as he closed the door behind him.

"Gooigi!" Luigi stood with Mario's help.

Gooigi found a faded cloth to wipe the key down in case it had traces of poison on it before handing it over.

"You're okay, Gooigi?" Luigi took Gooigi's hand as he accepted the key, "You're not hurt?"

Gooigi liked the feeling of being fussed over. He didn't know why, maybe it was because E. Gadd wasn't particularly affectionate, so he wasn't used to it? But regardless, he gave another thumbs up.

"Okay. Let's take this key and get out of here."

***


	10. Chapter 10

Luigi had the key in his hands as he approached the door, fiddling with it anxiously. He tugged on the collar of his shirt, gulping loudly.

"What if this isn't it?"

Peach placed a hand on his back, "Then we'll find it. You'll see."

Luigi offered a shaky smile in response to her warm one. He still shuffled his feet, though. He inserted the key, bracing for the lock to put up resistance...

...

It didn't turn.

Luigi rubbed his eyes until he saw stars, "Of course. Of _course."_

Gooigi pulled him away from the door.

"Why am I even surprised at this point." Luigi laughed, "I'm such an idiot for thinking this could end anytime soon."

He continued to laugh, his stomach flipping as tears gathered in his eyes. His throat was dry. His toes were cold and numb. He shook violently, his sniffles the only sound escaping him once the laughter had died down.

He leaned against the key, still embedded in the lock, _"I'm sorry. I don't know why I'm like this."_

"It's okay, Luigi." Mario lifted his head, wiping the tears from his face, "How long have you been at this?"

Luigi swallowed, trying to recall the last time he saw the sun.

"Um..." Luigi leaned into Mario's touch, "A-all night..."

Mario frowned, "Oh, bro..."

"Luigi..." Peach took his shaking hand, "I think you've reached your limit. Let's head back to the lab."

Luigi didn't protest. Gooigi activated the tv portal for them. As soon as Luigi registered the monitors and the faint smell of coffee, his legs gave out from under him and Mario was forced to catch him before he got hurt.

Luigi groaned as Mario took the Poltergust from him to lay him on his back. Luigi took his cap off to set it down on his chest, forcing breaths in and out of his aching lungs.

"Mario." he mumbled pathetically, "Don't leave. Please."

"I'm not going anywhere, bro." Mario ran a hand through Luigi's hair, "I'm right here. I promise, I won't leave."

Luigi deflated with a long exhale, "Okay. Thank you."

He was in and out of consciousness for the next few hours. At some point, Mario had laid down beside Luigi, holding his hand before drifting off. Peach sat on the floor, her dress billowing out around her. Gooigi was left to think again, mostly about himself. What he was made of. Who he was. Why he was living despite not being alive.

"Gooigi?"

Gooigi looked up at the sound of his name. Peach had taken her heels off, massaging her feet beneath their white stockings.

"How long have you been alive?"

Gooigi thought about it, but E. Gadd answered first, "A little over two days."

"Oh." Peach smiled at Gooigi, "That means yesterday was your birthday, right?"

 _"More like creation day."_ E. Gadd muttered.

Gooigi thought about it before giving a shrug and a nod.

"You haven't been alive for very long, then." Peach yawned into the back of her hand, "Oh my. Maybe I should rest too."

"I would strongly advise it." E. Gadd rolled his chair back to show off the monitor he had been scrutinizing, "The room we're trying to get to is full of traps. If you want to have a hope of defeating King Boo, the last thing you want is to be sleep deprived."

Peach shrugged, brushing down her dress to lie down, her skirt bunched around her ankles as she curled up into a ball.

"You too, Gooigi." E. Gadd added, "You've been out of your tank for far too long. Recall for a bit, alright?"

Gooigi made a bubbling sound of defiance.

"I mean it. Don't lie, you're tired."

Gooigi relented, if only to get the old man off his back. In the darkness of the lab, E. Gadd lifted his hands from the keyboard and rested them under his chin, his mind running a mile a minute.

Goodness gracious, he was getting too old for this.

***

Luigi was the first to wake up, a little disoriented from realizing he wasn't in his bed at home. A cool presence nuzzled into his side, and he instinctively started to pet it.

"Hey, Polterpup." he said sleepily as he sat up, letting Polterpup sit in his lap as he continued to pet him, "Where have you been?"

Polterpup cocked his head, his tongue lolling out of his mouth as he panted. He excitedly leaned into Luigi's hands, seeking more pats.

"Aw." Luigi scratched the side of his head, "Who's a good boy?"

Polterpup responded with a sloppy kiss to Luigi's face, making him chuckle.

"You're awake."

The sudden voice made Luigi jump, jolting Polterpup out of his hold and eliciting a whine from him.

"Luigi, my boy. Come here for a second."

Luigi stood up on shaking legs, watching how E. Gadd's glasses reflected the glow of the monitor in an eerie way, "What is it?"

The monitor was displaying a map of the floor with the locked door, showing a massive room with many connecting pipes and wires. It reminded him of a battle arena. It sent a chill up his spine.

E. Gadd finally swivelled in his chair to face him, "How do you feel?"

"Um..." Luigi stretched his back and felt his spine pop, "Honestly, I'm pretty sore. Have you just been sitting here the whole time?"

"Well, someone has to keep watch." E. Gadd's mouth opened wide in a huge yawn, "I'm exhausted, though. I think my eyes are starting to go."

"Your glasses are thicker than my hand."

"And yet they can't protect me against eye strain." E. Gadd rubbed his eyes beneath said glasses, _"Why am I so old..."_

Luigi glanced up at the map, a rock settling in the pit of his stomach.

"Are you hungry? I'm afraid I don't have anything aside from pre-packaged camping food, but you should probably have some kind of fuel before you go off into danger again."

Luigi lifted an eyebrow, "What are you doing?"

E. Gadd tore his gaze from the computer screen, "What?"

Luigi shook his head in disbelief, "Why are you worrying about me like this? You have no qualms about sending me off to who knows where, why is this any different?"

E. Gadd scratched his head, sighing in a defeated way that made him slump over his desk like a puppet with its strings cut.

"Because..." E. Gadd folded his arms in front of him, "I...feel bad about pushing you so hard. I heard you throwing up outside the arsenic room, and earlier when you collapsed, and seeing you cry so hopelessly...I don't know. It was a chilling reminder that my tunnel vision can get people hurt. I never wanted to hurt you, Luigi. I mean, I knew you were scared, but I didn't..."

He wasn't directly apologizing. Not once did he say that he was sorry, even though he expressed clear regret. Luigi supposed he shouldn't have been surprised, but it still stung.

"Anyway, I guess I'm just trying to make it up to you." E. Gadd procured a protein bar, "Eat at least a little bit, alright?"

Luigi shrugged as he took it, "Alright. It better not taste like copper."

As he peeled the wrapper back and took a small bite, he watched E. Gadd return to his impassive staring. He didn't even touch the keyboard, which was unusual for him. Looking at the monitor, Luigi could guess why. The room that likely housed King Boo was a mess of signals. He could almost imagine the thoughts racing through E. Gadd's head at a hundred miles an hour, no doubt trying to figure out why the signals were off the charts.

Luigi's mouth exploded with sensations, and he realized for the first time that night just how hungry he was. He scarfed down the rest of the protein bar in two bites, feeling as if it was the best thing he'd ever tasted.

"Hungry?" E. Gadd tossed a box at him, "Take 'em. I'll eat them all otherwise."

Luigi ate three more protein bars before he finally slowed down, his mouth dry from the nuts and peanut butter. He took a bite of a fourth, swallowing before he set the box down, "Do you have water?"

E. Gadd opened a drawer in his desk, revealing dozens of unopened water bottles, "I come prepared, as you can tell."

Luigi opened one and threw it back, gulping down half of it before he had to stop for air. Twisting the cap back on, he cast his gaze at his three companions, all of whom were still sleeping.

Luigi set everything on the ground, "Thank you."

"Hm?"

Polterpup returned to Luigi's arms, and Luigi was happy to give him pats, "I said thank you. For the food and water."

"Oh! You're welcome."

Luigi carried Polterpup to Mario's side, sitting against the wall with the ghost dog in his lap. Polterpup nuzzled into Luigi's cheek.

Luigi took the sides of Polterpup's head, "Are you not barking because people are sleeping?"

Polterpup panted, his mouth wide as if in a smile.

Luigi laughed, his first real laugh all night, "Good boy."

Polterpup responded with another sloppy kiss. Luigi gave him a few more pats before relaxing against the wall, his arm resting on Polterpup's head as he closed his eyes.

"Luigi?"

Luigi jolted. He hadn't meant to fall asleep again.

"Mario?" he sat up in time to see Mario rubbing his eyes, "Did you sleep well?"

"Well enough." Mario yawned as he stretched his arms high in the air, "What about you?"

Luigi lifted heavy arms to rub the sleep from his eyes, "I've slept better."

He dropped his hands only to find that Polterpup was still in his lap, sleeping soundly. Luigi pet him, and he leaned into the touch. He softly growled at something in his sleep, and Luigi smiled softly.

Mario took the hand that wasn't petting the sleepy pup, "How are you feeling?"

Luigi's smile fell as he gave a shrug, "I've been better."

If he was being honest, he felt ill. His stomach tangled into knots and his head pounded against his eyes. He almost felt like he should be in the hospital...well, considering he inhaled smoke and arsenic in the same night, that would make sense. He was still going, though. He didn't die in his sleep, so he took that as a good sign.

"I don't want to go back out there."

Mario sighed, "I know. I don't either."

Luigi took comfort in Polterpup's soft glow, "I can't remember the last time I was able to just lay down and catch my breath. I can't believe how much I realized I was taking clean air for granted. My throat is still sore from coughing."

Mario huddled up close to Luigi's side, joining him in petting Polterpup, "Was it this bad the first time you saved me? Or the second?"

Luigi shook his head, "It was still awful, and it gave me nightmares for weeks, but it wasn't this bad."

"You didn't have another nightmare?"

Luigi took a sharp breath of air, "No. I don't think so."

The two of them lapsed into silence. Luigi looked up to see that E. Gadd had fallen asleep with his head on the desk, snoring softly and drooling over the desk top. His forehead was on the spacebar of the keyboard, leaving an endless list of spaces on the screen.

"Mario? Luigi?"

Peach sat up, yawning and stretching. Her lip gloss had smeared over her cheek in her sleep, which she felt and wiped away with a thumb before scooting closer to the two brothers.

"Hiya, Peach." Mario brushed a hair behind her ear, "How did you sleep?"

She rested her head on the wall, "Okay. I don't know how you boys can sleep on any surface, my whole side is numb."

Mario shrugged, "Runs in the family. Our dad could sleep on any surface too."

Gooigi was the last to awaken. He fell backwards as soon as he emerged, scrambling back up with a spinning head. Polterpup jumped forward to catch him when he stumbled forward, and Gooigi pushed off of him to regain his footing.

He warbled in questioning, kneeling down in front of Luigi as Polterpup returned to his lap.

"Hey, Gooigi. How did you sleep?"

Gooigi gave a thumbs up, but then he made the same questioning warble. It sounded like he was confused about something.

Luigi figured he didn't mind playing detective for a bit, "Are you trying to ask me a question?"

A nod.

"Is it about something I said?"

Another nod.

"Is it about how me and Mario can sleep on any surface?"

A head shake.

Luigi thought back to what he had said before. What else had he mentioned?

"Is it about our dad?"

A third nod.

Luigi's eyebrows flew up, "Gooigi, are you asking about my family?"

Gooigi gave an enthusiastic nod, relieved that he was understood without having to talk.

"Wow." Peach said, in awe, "You understand him, Luigi."

"Well, I know what it's like to have to communicate non-verbally. Both me and Mario do." Luigi sighed as he dove backwards into very old memories, "Well, our mom and dad are both citizens of the Mushroom Kingdom, but they were actually born and raised in Italy. They moved back there after me and Mario grew up, and we still visit them occasionally. Our mom makes the best spaghetti you've ever eaten. Every time I taste it, I can't help but feel like I've made it home. Our dad was a private contractor and a plumber before he retired, and now he has a huge garden full of vegetables and flowers."

Gooigi hung onto every word. When you knew as little of the world as he did, everything was new and exciting.

"Me and Mario were plumbers too before Peach was kidnapped the first time. Anyway, they're the best parents I could have ever asked for. I try to call them every day if I have the time."

"Me too." Mario added.

"Yeah." Luigi was snapped back to the present when Polterpup kissed him, "Haha! Well, I don't know what else I can say about them at the moment. You can probably meet them once we get outta here."

Gooigi was intrigued, to say the least. He was still curious about something, though. He pointed at Mario, then at Luigi, tilting his head in questioning again.

"You want to know more about me and Mario?"

Gooigi nodded.

"Okay, well..." Luigi leaned back, absently petting Polterpup, "We're twins. I don't know how much you know about families, but it just means we were born to the same parents on the same day. Mario is slightly older than me. We're both thirty one years old. I remember opening my eyes as a baby every morning, and the first thing I saw was Mario. He used to put his arm around me if I was crying, and it would always calm me down. We couldn't even have separate cribs when we were little, or I would never sleep."

Mario put his arm around Luigi, who let out a huff of a laugh.

"Thanks, bro." Luigi continued to reminisce, "Once we were old enough to have our own beds, we had beds that were side-by-side, and then we had a bunk bed. I was a bit of an obnoxious younger brother, honestly. I followed Mario wherever he went, I wore similar clothes to him, I did the same things he did...it's a little embarrassing looking back, but I didn't know any better."

A proverbial light bulb went off in Gooigi's head. No wonder Luigi was so stuck to Mario's side. Mario was to Luigi as Luigi was to Gooigi; A figure who could provide direction in an uncertain world, whether through confidence or experience. He almost felt as if...he hadn't been fair to Luigi. Maybe it was his inexperience with the emotions of others, but he had no right to be baffled at Luigi's dependence on his brother when Gooigi was essentially doing the same to him.

Luigi watched the gears turn before asking, "What are you thinking about?"

Gooigi waved his hand dismissively, wondering if this was what embarrassment felt like.

"Well, okay." Luigi gave Polterpup one more pat before standing up, "Anyway...I guess..."

Mario stood up with him, a hand on his arm.

"Okay, first things first..." Luigi retrieved the box of protein bars, "Is anyone hungry?"

***


	11. Chapter 11

Luigi opened the second to last locked room in the mansion with the key. It swung open, and Luigi's flashlight swept across the room.

This one was a bedroom too, but it was much more lavishly decorated, with lace curtains, patterned rugs, and all kinds of furniture, including a giant sofa and a king-sized bed. However, it was all purple and not green, which put them at ease at least somewhat.

Luigi's flashlight beam landed on a tiny figure in the center of the massive room, and his heart stopped.

A pink ghost cat sat with her back to him, her tail flicking as if in impatience. Inside her translucent body was a key, which she had clearly decided to swallow for safe-keeping.

Mario picked up on Luigi's apprehension first, _"Luigi?"_

Luigi's mouth opened and closed a few times, his lungs refusing to allow him any air as he tried to form words but failed.

Gooigi took Mario's shoulder, putting a finger to where his mouth would be if he had one.

Luigi exhaled long and slow, his nerves shot and his mouth dry. The beam from his flashlight was shaking with his fear.

"Polterkitty." Luigi said simply, "She is the biggest headache in this whole building."

Polterkitty turned towards them, meowing indignantly. Polterpup growled at her, barking a few times for good measure as she slowly approached.

"Well..." Luigi's thumb hovered over the strobe button, "Here goes nothing..."

As soon as he flashed the strobulb, Polterkitty exploded outward into a monster ten times her usual size, her evil meows echoing in the room and scaring Polterpup from the room. She scrambled away, and Luigi firmly planted his feet on the ground.

"Okay, now we need face away from her." Luigi turned back towards the door, despite how wrong it felt to turn away from the danger, "Hold still. Don't look at her."

This was the point when Luigi had to force himself to hold still and listen. Polterkitty's claws scraped the carpet as she pattered across it, and the hairs on the back of Luigi's neck stood on end. He fought against every instinct he had to run or turn back. He simply stayed as still as he possibly could.

Polterkitty huffed, blowing air over their skin and causing it to prickle with goosebumps, and Peach gasped and turned reflexively, making Polterkitty flee.

Luigi whimpered hopelessly, "Peach!"

"Sorry! I'm sorry!" she covered her face in embarrassment.

Polterpup jumped back through the wall, sniffing the ground for wherever Polterkitty had disappeared to.

Luigi held back tears. His head was swimming, though the fact that he was rested and fed made it not as bad as it would have been. He bit a fingernail beneath his glove, wondering just how much longer this night was going to last.

Gooigi gurgled as he pointed his dark light at the place in the ceiling where the ghost cat had disappeared to.

"Okay..." Luigi rubbed his eyebrows, "Okay, we can still do this. Follow me."

On the next floor up, Polterkitty was hiding above the rafters, hissing when they came into view. Polterpup hid behind Luigi's legs, trembling, but still trying to bark angrily at Polterkitty.

"Okay, you three go over there. Just hide for a bit." Luigi pointed his flashlight at a pile of furniture, "I've dealt with this alone before. Gooigi, Recall."

"What?" Mario took his shoulders as if to shake some sense into him, "Are you crazy? If you let her sneak up on you, you could die!"

Luigi trembled in Mario's hold, "You think I don't know that? I'm worried about _you_ guys. I've done this before, I can do it."

"I know you can." Mario loosened his grip, "But just because you can doesn't mean you should have to. You're shaking like a leaf."

Luigi's lip quivered.

"Please, let me help you." Mario said gently, "It'll be easier with both of us."

"No, please. I can't let you get hurt again."

_"Luigi."_

Luigi flinched at the stern tone his brother used, usually only reserved for someone who had gotten on his bad side. Mario's sharp expression fell when he saw the tears glistening in Luigi's eyes.

"Luigi, You're my little brother." Mario said, "My _baby_ brother. I used to watch you follow me everywhere, copy my movements and ask for everything I asked for, and I remember feeling so protective of you. I wanted to keep you out of danger at all costs. If anything ever happened to you, I would _never_ forgive myself."

Polterpup ran into Luigi's legs, and Luigi frowned at the floor.

"We're a team, right?"

Luigi laughed, and this time he really felt it.

"Yeah, bro. We are." Luigi linked arms with him, "Okay. Turn away from Polterkitty, and don't turn around until she's ready to pounce."

The four of them turned around while Polterpup escaped again. The sound of Polterkitty stalking towards them made them shiver, but Luigi was determined to wait for the perfect moment.

She took another step towards them.

Luigi was feeling a cold numbness wash over him. The dread was like a rock in his chest.

She took another step.

His heart was beating too fast, but he couldn't breathe. He wasn't getting enough oxygen.

Another step.

He could feel her breath on his neck. He wanted to abandon the plan, but he couldn't even move his eyes. Staring at the same spot for so long was making an impression on his retinas, and the world appeared to fade.

The steps stopped.

She wasn't going to pounce? Luigi couldn't even look to see what she was doing. She could have disappeared for all he knew. He was the one with Poltergust, so he was the only one who could attack her, but something about this situation was just too...

He heard the sound of her rising up on her haunches, but he couldn't move at all. In the time he knew they would be sliced, he could only think to choke out;

_"H-help."_

Mario snatched up Luigi's flashlight and hit her with the strobulb, "LUIGI!"

Luigi sprang into action, bringing out the vacuum and sucking her up into it. She tried to run, of course, but both Mario and Luigi were pulling the trigger, tugging with all their might as they were dragged all around the room. One of Polterkitty's three tails got stuck in the end of the vacuum, and the force made Mario let go and skid a few feet away, but Luigi was prepared. He yanked backward, slamming her into the floor several times, back and forth, until the tail came clean off and disappeared into the vacuum.

That seemed to anger Polterkitty, as she didn't leave the room this time or take her time in pouncing. She launched herself at Luigi, scratching three massive claws across his face.

"Ow!" Luigi hit the ground hard enough to knock the wind out of himself.

Gooigi quickly hit Polterkitty with his strobulb, drawing her attention away from Luigi as Mario and Peach rushed to his side.

 _"Ow ow ow ow ow ow!"_ pain ricocheted across Luigi's skull as he held the wounds. He felt the stickiness, and his fears were confirmed when his hands came off bloody.

He felt his eyes flutter closed, and Mario caught him as he fell.

"Luigi!" Peach retrieved a handkerchief from her pocket to press into the wounds. There was a cut across his forehead, one under his eyes, and one across the top of his nose.

"Mario!" Luigi reached for him, on the verge of losing it, "HELP ME STAND UP!"

Gooigi was crushed by Polterkitty, returning to his tank as she charged again.

Mario had just hoisted Luigi to his feet when Luigi flashed the strobulb, activating the vacuum before Polterkitty could escape. Mario and Peach held the nozzle of the vacuum with him this time, ramming into various furniture around the room as they were dragged behind her, until Luigi had another chance to slam Polterkitty multiple times into the ground. Her second tail snapped off. Only one left to go.

Polterkitty jumped through the wall, and for the moment, it appeared as if she was gone.

Luigi was shaking violently. He could barely keep a grip on the flashlight he was shaking so badly. It didn't help that his hands were sweaty enough to swim inside his still-bloody gloves, and he was cold all the way down to his bones.

Mario reached for him, "Lui-!"

 _"Don't touch me!"_ Luigi said, more harshly than he intended, _"Don't touch me or I'll lose my nerve!"_

For the first time in this entire ordeal, Luigi was _angry._ He was more angry than he'd ever been. Having blood on his hands again brought the memory of Mario's still body back to the forefront of his mind. If Mario distracted him now, he was sure he would lose this sudden rush of adrenaline and fall unconscious...or worse.

Luigi turned around, a claw three inches from his eye. It was too late to strobe her. It was over. He was-!

A flash of light blinded him, and Polterkitty froze.

Peach was holding Mario's flashlight that he'd dropped in the scuffle, "GET HER!"

Luigi switched the vacuum on. Pull. Switch. Slam, slam, slam. He went through the routine like clockwork, moving almost on muscle memory as he wrestled with her, getting closer and closer to pulling her inside the Poltergust. She clawed at him and at the air on her way in, screeching at the top of her lungs, until finally, she disappeared through the nozzle of the vacuum, and it exploded in a golden light as it expelled the key. After that, all was quiet.

Luigi's ears were ringing.

Gooigi re-emerged from the tank, trotting over to the key and picking it up. He brought it back to Luigi, and almost flinched back at the sight of him.

Mario and Peach approached cautiously. Luigi's hair was sticking out in all directions beneath his hat, which had been knocked askew. His gloves and the sleeves of his shirt were covered in blood. Blood also dripped from his claw scratches, his eyes wide and wild. He held the Poltergust's handle like a weapon, his stance hunched, ready for something else to jump out at him with no warning.

"Luigi-!" Mario winced as Luigi pointed the Poltergust at him, "Bro, it's okay. You did it. You can relax now."

Luigi lowered the nozzle, "Really? There's nothing else?"

Mario looked around, glancing over Peach and then Gooigi, who offered a shrug.

"Yeah. There's nothing else." Mario held his arms out, "It's okay, Luigi. You're safe now."

Luigi let his arms relax until the handle touched the floor. He took another second to process his pain before his legs collapsed from underneath him and he caught himself on his knees and forearms, _"Thank god..."_

Mario hugged him, then Peach, then Gooigi. It was a little stifling, but being surrounded by so much warmth, support, and love was really nice. He felt safe. He felt okay.

Luigi lifted his arms to hold the ones that were wrapped around him, both solid and gelatinous.

"Can we stay here?" he said under his breath, "Just for a little bit?"

Mario gave him a gentle squeeze, "Yeah, bro. We'll stay here as long as you need."

Luigi's head lolled to the side, and he closed his eyes. He focused on his breathing, on the smell of Mario's shampoo, Peach's perfume, and ectoplasmic copper that always seemed to cling to Gooigi.

Polterpup wiggled into his arms, and if he was being crazy, he almost felt like he was right at home.

***

**Notes for the Chapter:**

> Is anyone else as terrified of Polterkitty as I am?


	12. Chapter 12

Luigi stood in front of the door, the key in his hands. This was it. There were no more rooms left to explore. If this key didn't fit, then they would have to give up on confronting King Boo and find some way to escape. If that was even possible.

Still. He found that he couldn't. His feet were glued to the floor.

"Luigi." Mario put his hands over Luigi's as they twisted around the key, "What's wrong?"

Luigi shook his head, "It's...it's nothing."

Peach lifted Luigi's chin to look her in the eye, "Luigi, it's going to be okay. If this isn't the right key, then we'll figure something out."

"You're right, you're right." Luigi huffed, "Okay, here goes..."

Luigi inserted this third key, pausing to take a breath before attempting to twist it...

...

...

_Click!_

The key slid easily through the lock, disappearing once it was used. Luigi almost couldn't believe it. He kept his arms outstretched for another couple of seconds before he reached for the doorknob and twisted it, pushing open the door on rusted, squeaky hinges.

As they walked inside, three flashlight beams descended on the walls, which were covered in various empty picture frames. The whole room was made out of concrete from floor to ceiling, the only notable features in it being the slight dip in the floor which brought it a little lower than the door they just left, and the fact that there were grates along the walls and sprinklers on the ceiling.

Luigi's footsteps echoed in the silence. Gooigi huddled close to him, his eyes focused on the ceiling.

"Hello?" Luigi called out timidly, flinching when his voice echoed harshly off the walls.

"Well well well..." a familiar ghostly voice rang out, "You finally decided to show up."

The sprinklers turned on, and Gooigi screamed.

"Gooigi, recall! _Recall!"_

He got the message, though he was already half-melted by the time he successfully returned to the tank. Luigi only hoped that most of him was safe.

Luigi shivered in his newly sopping-wet clothes, squeezing his eyes shut when water coated his eyelashes, "King Boo!"

The sprinklers shut off, but they were all still ankle-deep in water. Gooigi would have to sit this one out, it seemed.

King Boo hovered through the floor, splashing up the water, his tongue lolling out of his mouth as his shadowed, purple eyes landed on his arch-nemesis, "It took you long enough! Are you the world's slowest heroes or what!?"

The words were out before Luigi could stop them, "Oh, I'm sorry that our traumatic experiences don't conform to your schedule! I'll try to get traumatized sooner next time! I'm sure I can get to it between running for my life and finding three seconds to get a bathroom break!"

"Well, _someone's_ bolder than I remember!" King Boo laughed, "Well, it doesn't matter. I have the most robust collection of ghost portraits that anyone has ever seen, and you, Luigi, will be the _pride_ of my collection!"

He disappeared, and all the lights cut out.

Luigi didn't think about what King Boo had said, "Ready, Bro? Princess?"

They each put a hand on his shoulders. It helped to ground him.

Now, he had no idea what to expect, so he basically just twisted his flashlight everywhere to try and catch King Boo off-guard. Mario did the same, holding Peach's hand in his left hand. It was unnaturally quiet, to the point where Luigi wasn't sure if there was a battle at all and they were just meant to suffer in silence. _Well, that's not fair!_ he thought bitterly, _At least give us a chance, you oversized marshmallow!_

A ripple in the water was his only warning before a chill passed through him and he was suddenly having an out-of-body experience.

He dropped his flashlight as another beam landed on him. He couldn't turn his head, but he knew it had to be Mario.

"Luigi!?" Mario's voice was shaking, "You..."

Gooigi gave him a mental kick from inside the tank, and Luigi's vocal chords finally began to work.

 _"Bro..."_ he forced between his teeth, _"S-s-s-stro..."_

Mario flashed the strobulb before he could finish, and King Boo came flying out of Luigi. He scooped up his now-wet flashlight, turning on the dark light to force him out in the open. He then grabbed King's Boo's tongue in the vacuum, slamming him into the shallow water multiple times until he spun in a circle and launched him at the concrete wall. He flattened against it before disappearing again, and the lights came back on.

"Luigi, are you okay!?" came the worried voice of Princess Peach.

Luigi sneezed, "Yeah, fine. Just really cold."

Peach hovered off the ground, ghostly apparitions holding her up and making her fly backwards with a scream.

Luigi reached for her. He brushed her fingertips.

She flew into one of the empty frames feet-first, disappearing up to her knees, then her waist while she pushed against the wall with her arms.

Luigi ran to the wall, "Princess!"

"Luigi! Mario!"

Her grip slipped, and she plummeted into the frame. Frozen in the painting were her outstretched arms and horrified expression.

"Peach!" Luigi fiddled with the Poltergust's handle, "D-d-don't worry! I'll-!"

"I'll be taking that!" King Boo snatched the painting off the wall, "Wow. She really is a beauty, isn't she?"

He laughed as he disappeared with the frame.

"Hey!" Mario called out after him, _"You'll pay for that!"_

The lights cut out once more, but this time, Luigi knew what to look for. Gooigi couldn't join them in the fight because of the water, but because of the water, the slight rippling gave King Boo’s location away whenever he got close to them. Luigi stayed as still as he could until he heard the smallest of splashes and he turned with the dark light.

King Boo was halted, his tiny arms covering his face until he was stunned and Luigi could attack once again.

"HYAH!" Luigi slammed King Boo one last time before he escaped.

Luigi heard someone slip behind him, and he reached out without thinking, catching Mario's hand as he flew away.

"Luigi!"

"Mario!" Luigi dropped the flashlight to hold Mario with both hands, bracing against the ground.

He could feel the color drain from his face as he saw where Mario was going.

"Mario, no!" Luigi held on tighter, "Don't leave me! Don't go! Please! I can't lose you now!"

"I'm not going anywhere!" Mario reached out with his free hand to shake Luigi's shoulder, "I'm still here! I'm rooting for you! You're going to defeat King Boo like you always do, and we're going to get out of here! You're going to be okay, Luigi! You're going-!"

Luigi lost his grip, and Mario cried out as he disappeared.

"NOOO! MARIOOO!"

Mario slid easily into the picture frame, and Luigi fell to his knees, soaking his pants in the water.

"Now, _that's_ a beauty!" King Boo admired the painting before taking it off the wall, "Don't worry, Luigi. I'll make sure your brother's painting is right beside yours!"

Luigi held himself up, staring at his hands in the water. The blanket of sorrow over his heart made him feel so heavy. He realized that King Boo could easily have just stuffed all three of them in the paintings at the same time, but he was doing it systematically and slowly just to toy with them. Luigi's view was distorted by the tears that fell into the water beneath him, and he watched the rings that flowed outward until they dispersed.

Luigi lifted a wet hand to his earpiece, "E. Gadd? Can you hear me?"

All that came back was static. It seemed the concrete walls were too thick to transmit signals.

He was alone.

A sharp feeling hit the back of his head, and he leapt to his feet. No, he still had Gooigi. He hadn't lost yet. He couldn't lose his focus now. How long had he been sitting around? Was King Boo-!

That icy feeling hit him again. No! He hadn't been paying attention! He cursed himself for falling so easily to grief while forgetting that someone was coming after him. He tried to break free, tried to reach for his flashlight, but even though Gooigi was helping him stay present, it still wasn't enough.

"Ow! Ow!" Luigi's head spun as his muscles spasmed. He could feel himself growing weaker, like King Boo was sucking the life right out of him. He tried to stay steadfast in his goal, but the pain was clouding his senses, "Ow... _ow..."_

He fell backwards, still futily reaching for the flashlight. He was on the edge of consciousness. Gooigi was screaming in the back of his head, but if anything, it only added to his pain.

"Oh hoho!" King Boo emerged from Luigi's heart, making his already-weakened body convulse with the sudden warmth, "I didn't think it would be quite this easy! You really are just Mario's shadow!"

 _No I'm not!_ he tried to fight King Boo's hands on him, _Don't touch me! Leave me alone!_

"Oh my! You're looking worse for wear, aren't you?" King Boo brushed his hair back, "Here, let me fix you up a bit. I want you to look nice for the picture, after all!"

Luigi closed his eyes, feeling the tiny, sharp-cold arm run across his skin and wishing he could push it away. Was this it? Was he dying? Did he fail?

"Perfect!" King Boo replaced his hat, straightening it on his head, "Now, say cheese!"

Luigi felt himself be picked up, floating towards the picture frame. As it entered his vision, he was overwhelmed by apathy. Maybe being a pretty picture on a wall wasn't such a terrible fate. At least then the pain would stop.

His legs went numb first, frozen like they were encased in concrete. He knew he should be afraid, but he couldn't be bothered. He was tired. He was ready to sleep.

And then Gooigi disappeared from inside his head. The Poltergust had entered the painting.

Luigi's eyes snapped open. Gooigi had been pleading with him to snap out of it, his fear hitting Luigi's consciousness stronger than it ever had. Gooigi had been truly terrified for the first time in his short life.

And now he was gone.

Luigi felt a surge of determination warm him down his fingertips. He was still sluggish, but he reached for his flashlight as his waist disappeared into the painting, and then his chest-!

 _Got it!_ Luigi found the dark light button and turned the flashlight towards himself.

"Aw, he's fighting back." King Boo drawled, "How cute."

Luigi ignored him. His ears brushed the canvas before he began to re-emerge, slowly climbing out of the painting, with both hands still on the flashlight.

"Huh?" King Boo pushed him harder, "Hey! You can't do that! Play nice!"

Luigi kicked against the painting, emerging up to his knees before he was hit again with that paralyzing cold.

_"Get back in your painting, you stupid plumber!"_

Luigi grit his teeth as he sank back into the canvas, his arms shaking as he held the flashlight. King Boo tried to wrestle it out of his hands, but he put every last drop of energy in his body into holding that flashlight for dear life. His head disappeared into the painting, clouding his thoughts, his elbows, almost down to his wrists, but he still didn't let go. He wouldn't let himself falter now.

Just when he thought he couldn't hold on much longer, a third arm reached out beside him, gripping the flashlight on top of Luigi's hand. The arm was translucent and green.

Luigi doubled down on his efforts to keep fighting. Gooigi's arm yanked on the flashlight as he regained his footing, his other arm reaching out to grip Luigi's wrist. He tugged on Luigi's arm, pulling him out through the beam of the dark light. Luigi's head emerged from the painting, and he took a gasp of air.

"No! How are you doing this!? You can't do that!" King Boo tried to shove him, _"Stop fighting!"_

Gooigi's right arm disappeared, returning with his own flashlight. With the two dark lights working together in tandem, King Boo didn't stand a chance.

"That's it!" Luigi braced against the frame with his arm, "Keep going!"

Gooigi emerged first, his foot connecting with King Boo's face. He recoiled, and Gooigi gave Luigi a thumbs up as he recalled. Luigi launched himself out of the frame, sucking up King Boo's tongue and slamming a third time.

"NO!" King Boo screamed as he was sucked in, "I'LL GET YOU FOR THIS, LUIGI! I'LL DESTROY YOU IF I HAVE TO!"

"You already have, you monster!" Luigi pointed the vacuum nozzle at the ground, stepping on it as he squashed King Boo into the ground, "You've already had the last laugh! I have nightmares about you every night! You're looking at a broken man, King Boo! All I've ever wanted was for _you to leave me alone!"_

Luigi stomped on the nozzle again, and King Boo looked up as he was pulled further through.

Luigi's voice dripped with malice as he said, "Send Hellen my regards, won't you?"

And with one final stomp, King Boo was inside the vacuum, making a popping sound as he vanished.

Luigi fell forward, first on his knees, then on his stomach. The water drained from the room, and he was left lying on the concrete floor, his heart pounding and his lungs wheezing.

"Luigi?"

Luigi blinked, his vision swimming.

"Luigi, my boy! Are you okay!? Please get up!"

Luigi pushed off the floor. E. Gadd was hovering over him, along with Gooigi, Peach, and to Luigi's relief, Mario.

"Luigi." Mario lifted him into a hug, "See? I told you you could do it. I'm so proud of you."

Luigi shook with both tears and laughter, "Thanks, bro. It wasn't easy."

"I can tell." Mario held him at arm's length, "You look like you have one foot in the grave."

Luigi thought back to what King Boo had done, "Wait, weren't you..."

Gooigi was standing there, too. The water had drained, and Gooigi could safely stand on wet surfaces so long as there wasn't enough to sink into.

Luigi smiled, "You freed them, didn't you?"

Gooigi nodded.

"Thanks, Gooigi. And thanks for saving my hide back there. You're a hero too, you know."

Gooigi's eyebrows lifted as he pointed at himself.

"Yes, you!" Luigi laughed again before falling into Mario's hold, "Ugh..."

"You're exhausted, huh?" Mario sat him up, "Want to go sleep in an actual bed?"

Luigi's head hung, "Carry me?"

"Luigi, you're thirty one years old!"

"Pleeeeease?"

"Mamma mia..." Mario rolled his eyes, "Fine, fine. Who wants to carry the Poltergust?"

Peach volunteered, so the five of them headed back to the elevator to return to their rooms. Mario set Luigi down in his bed, and he was out the second his head hit the pillow.

***


	13. Chapter 13

It was 9:30 in the morning by the time anyone was up. Luigi felt the sunlight warm his face through the torn curtains, and he cried. Gooigi pulled the curtains back to feel the warmth, astounded by how bright it was. Peach had the biggest bedhead, but Mario was a close contender despite having shorter hair. Luigi brushed his teeth in front of the mirror in the bathroom, Polterpup flying in lazy circles around his ankles.

Despite the fact that there were three bathrooms, they each took turns taking showers, the rest gathered around outside it to play board games and eat real food. E. Gadd joined them around 11, his one strip of hair sticking out at all angles and making him look even more like a mad scientist. Peach was the only one who wore pajamas before her shower, and they were covered in a colorful peach pattern.

The domesticity of the situation was foreign to Gooigi, but he wasn't complaining. He knew everyone needed to slow down after everything that happened, and he really felt like a member of a big family when they were all together like this.

By the time everyone was packed and ready to leave, it was almost 2 in the afternoon. Many of their things had been destroyed in the hotel, but they salvaged what they could, loading everything up in Peach's bus or otherwise in E. Gadd's car.

"Well, I think that's everything." E. Gadd closed the trunk of his car, adjusting his glasses when they fell askew, "Are you ready to go, Gooigi?"

Gooigi's insides gave a hearty pang.

It was time for them to part ways.

"Huh?" Luigi took his hand, "Gooigi, what's wrong?"

Gooigi stared at the ground, unable to find a way to communicate his thoughts.

E. Gadd frowned, "You're going to miss him, aren't you?"

Gooigi didn't respond at first, but eventually, he nodded.

"Aw." Luigi turned him to face him, "This isn't goodbye forever. We'll see each other again soon."

Gooigi didn't move. He just continued to stare at the ground like it was the most interesting thing he'd ever seen.

Luigi took each of his hands between them, "I'll miss you too, Gooigi. I'm honored that I got to know you. I'll see you later, okay?"

Gooigi didn't give any indication that he had heard him, but he did squeeze Luigi's hands, his fingers caving around them as they weren't as solid as flesh and bone.

Gooigi forced air through himself, moving the goo in his body in a way he wasn't used to;

_"Doonn't ggo, Luuiggiii."_

Luigi's heart twisted.

E. Gadd crossed his arms, leaning back against his car, "I think he really admires you, Luigi. Talking is really unnatural for him, so the fact that he's trying to verbalize that he doesn't want you to go just shows how much he's going to miss you."

Luigi sighed, long and slow.

"Haha." he shook his head, "I never thought I'd feel so much like the older brother."

Gooigi gave a slow nod until he actually processed what Luigi had said, when he snapped his head up at the implication.

"Yeah, you heard me." Luigi tapped his shoe on the road, "You were modeled after me, you took guidance from me, we care about each other...I mean, that's what family is, right?"

Gooigi let go of Luigi's hands to envelope him in a hug, which Luigi returned firmly. The way Gooigi could feel Luigi's arms around him, the way his goo caved in his hold...it made him feel safe. He had been through a lot with Luigi, and he was honored that these memories with him were the first of his life. He would hold onto them forever.

Finally, after steadying himself a bit, Gooigi broke the hug, his eyelids lifted in an approximation of a smile.

As they parted ways, Luigi waved at him from the window of the bus, which Gooigi returned until they drove down different roads, and the bus disappeared over the hill.

"Don't worry, Gooigi." E. Gadd assured him at the wheel, "You'll get to see them again very soon, I guarantee it."

Gooigi couldn't wait. Until then, he would find a way to preserve these precious memories.

***

Luigi absently flipped through TV channels on his favorite armchair, just curious about what was on. Mario was up before him, rummaging around in the kitchen for who knows what. As soon as he saw Luigi, he put down whatever he was doing and headed over to him.

"Hey, Luigi."

"Hey, bro."

"Any nightmares?"

"No."

"You had breakfast this morning?"

"Yeah."

"Are you just answering my questions randomly?"

"Nope."

"Okay, just making sure."

Luigi sighed, turning the TV off, "You know, Mario, you don't have to keep fussing over me. I'm fine."

"Uh huh." Mario lifted one eyebrow, "That's what you said when you woke up screaming and ran to the kitchen to wash your hands because you were convinced they were covered in blood."

"Shut up, bro. You know what I mean." Luigi huffed, standing up to face him properly, "I know, I still have problems, but you aren't helping by interrogating me three times a day. Just lay off a bit, alright?"

"Alright, alright. I'll leave you alone."

"Thank you." Luigi sat down as Mario left, reaching out to prompt Polterpup from the other room to sit beneath his arm, "Sheesh. It's like he thinks I'm a child."

Polterpup barked.

"Yeah, that's what I said!" Luigi pet him as he kept talking, "Ah, well. I guess I can't blame him for worrying about me. I'd do the same in his shoes."

It was then that the TV turned by itself, displaying a screen of static. Luigi hid behind his armchair, remembering what happened the last time his tv had done this.

 _"Oh, no you don't."_ Luigi reached behind him for something he could use to defend himself, and his hand closed around a broom handle, _"I'm not helping you this time, old man! Come at me!"_

Instead of displaying E. Gadd's face however, a shape broke through the static. First, a hefty book, taller than Luigi's head, landed on the floor. Then, a polaroid camera, not unlike one Luigi had himself in his room. It made him realize that it wasn't E. Gadd on the other side of that screen.

A green figure stumbled through the tv before it switched off again, the VB clearly visible inside its body.

Luigi dropped the broom, "Gooigi?"

Gooigi stood up, giving a thumbs up once he'd stopped wobbling.

Luigi ran to him, "Gooigi!"

Gooigi met him halfway, stepping over his things to give Luigi a crushing hug.

"Gooigi! It's really you!" Luigi pulled back, "Wait, let me look at you! Oh my goodness! I missed you so much!"

Gooigi nodded, warbling in agreement.

"Luigi?"

"Mario!" Luigi gestured to their unexpected guest, "Look who it is!"

"Gooigi!" Mario offered a hug, which Gooigi returned enthusiastically, "It's so good to see you again! What have you been up to?"

Gooigi perked up, turning back to the book and the camera he'd brought with him. Opening the book on the floor, it became obvious that it was a photo album. The first photo was of Gooigi in front of the Gloomy Manor where E. Gadd did a lot of his ghost research, surrounded by friendly greenies. The next few photos were from various haunted mansions, some without Gooigi, and some where he'd pointed the camera towards himself. In one of them, he was happily smiling in front of a hammer that was charging towards him in the background. That one made Luigi chuckle.

"Please tell me how this one ended." he said, "Did you catch him?"

Gooigi nodded, rubbing his fingernails on his chest.

"Oh, sure. No sweat." Luigi turned the page, only to find it blank, "So that's it so far. Have you been out ghost hunting all week?"

Gooigi nodded again.

"Wow. I'm proud of you, bro." Luigi gently hit his shoulder, "Maybe I'll go with you one of these days. You can keep me safe, huh?"

Gooigi rippled with laughter, shoving him in mock annoyance.

"Haha! Hey, I mean it. I'm impressed." Luigi took the camera in his hands, "Is that why you brought these over? To make new memories?"

Gooigi nodded, placing one hand on the camera with the other on Luigi's wrist.

"Yeah! Let's get a picture!" Luigi switched a few settings on the camera, turning it towards the three of them with a smile, "Say cheese!"

Gooigi watched the shutter go off, and he knew he wouldn't forget this for a long time.

_Snap!_

THE END

**Author's Note:**

> Come say hi to me on tumblr! marshemillow.tumblr.com


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